Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/109

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loured variegated Mufcle. n. The grey filiated Mufcle. 12. The great Newfoundland Mufcle. 13. The great Canada Mufcle.

Of thofe ufually known in cabinets, under the name of Pin- na marina, we have the following: 1. The common great pinna, variegated with grey and red. 2. The fmaller whitiih aculeated Pinna marina. 3. The fmall reddifh acu- leated Pinna. 4- The Pinna of the fhape of a ham, com- monly called the bam Pinna. 5. The larger fpinning Pinna, called the ftlk Pinna, becaufe of the great quantity of filk which it (bins. 6. The fmaller Pinna marina, called Pinna tridacna by Rondeletius. 7. The Pinnopbylax; this is a large {pedes, fo called by Rumphius, from its often affording a lodging to a fmall crab. 8. The duck-bill Pinna. Of thofe Mytuli, which are of a more elate figure and equila- teral, wc have the following: 1. The white tender Mufclt; this when poHfhcd, is kept in cabinets under the name of the filver fhell. 2. The black Pholas Mufcle. 3. The yellow Pholas Mufcle. 4. The light and thin Mufcle, open in every part with a trunk. 5. The lefs open Mufcle, with a trunk. 6. The dufky- coloured Mufcle, from the ifle of Papous; this, when its outer coat is polifhed off', makes a very beautiful figure, and is found to be liniated within the {hell with brown and bluilh fafciae, and in this ftate is a remarkably elegant {hell. See Tab. of Shells, N°. 19.

Of the Tellina, which are oblong and flat {hells with equal extremities, wc have the following fpecies : 1. The violet- coloured Tellina, 2. The violet Tellina, with four white zones. 3. The fmooth Tellina, elegantly variegated with pale red and white fafciae. 4. The hairy Tellina, of the Me- diterranean fea. 5. The larger hairy Tellina, of the ocean.

6. The Canada Tellina. 7. The Tellina of the Azores ilhnds. 8. The great Newfoundland Tellina. 9, The fmall Canada Tellina. 10. The Saint Saviriiarv Tellina. This lafr. is often found polifhed m our cabinets, and then is very ele- gantly variegated with rofe-colour and a hi very white. Thefe are all the known Tellina, with equal extremities.

But of thofe which have the two ends unlike, we have the following fpecies : 1. The reddifh-beaked Tellina, refembling a furgeon's forceps. . 2. The yellowiln forceps Tellina. 3. The Tellina of the fhape of a knife. 4. The long-beaked Tellina. 5. The rough Tellina, called the cat's-tongue Tel- lina. 6. The fafciated and radiated rofe-coloured Tellina.

7. The orange-coloured Tellina, doubled on one fide, and dentated at the edge. 8. The leaf Tellina; this greatly re- fembles the leaf of a tree. 9. The white granulated Tellina. 10. The reddifh tranfverfely ftriated Tellina. ii. The flat- ted and truncated Tellina. 12. The violet Tellina, with a flriatcd apex. 13. The yellowifh Tellina, with a ftriated apex. 14. The reddifh Tellina; this is an elegant {hell, though little variegated. Hift. Nat. Eclair, p. 326.

The common fea Mufcle has, from its being always found fattened to the rocks, been fuppofed by many wholly incapable of progreflive motion; but this is an erroneous opinion. It is a common practice in France at fuch feafons of the year as do not afford fun enough to make fait, to throw the com- mon fea Mufcles, which the fifhermen catch about the coafts, into the brine-pits. They have an opinion that this renders their flefh the more tender and delicate, as the rain which falls at thefe feafons makes the water of the pits much lefs fait than the common fea-water. The Mufcles are on this occafion thrown carelefsly in, in feveral different parts of the pits; yet, at whatever diftances they have been thrown in, the fifhermen when they go to take them out, always find them in a clufter together; and as there is no current of wa- ter in thefe places, nor any other power of motion which can have brought the Mufcles together, it feems very evident that they mutt voluntarily have marched from the places where they were at firff, to have met thus together. This progreflive motion is wholly performed by means of what v/c call the tongue of the Mufcle, from its fhape; but, from its ufe in this cafe, appears rather to merit the name of a leg, or an arm, as by laying hold of any diftant fubftance, and then forcibly contracting itfelf again, it draws, along the whole body of the fifh; the fame part, when it has moved the ani- mal to a proper place, ferves alfo to fix it there, being the organ by which it fpins the threads which we call its beard, by which it is held to a rock, or to another Mufcle. The motion of the Mufcle, by means of this part, is juft the fame with that of a man laid flat on his belly, who would draw himfelf along by laying hold of any thing with one hand, and then drawing himfelf to it. Mem. Acad. Par. 17 10. Mufcles arc well known to have a power of fattening them- felves very firmly either to ftones, or to one another's fhells, in a very ftrong and firm manner; but the method of doing this was not well underftood, till the obfervations of the ac- curate Mr. Reaumur explained it.

Every one who opens and examines a common Mufcle will find, that in the middle of the fifh there is placed a little blackifh or brownilh body refembling a tongue; this in large Mufcles is near half an inch long, and a little more than a fixth of an inch in breadth, and is narrower at the origin than at the extremity; from the root of this tongue, or that part of it which is fattened to the body of the fifh, there are pro-

duced a great number of threads, which when fixed to any folid fubfiance hold the Mufcle firmly in its place: Thefe threads are ufually from an inch to two inches in length, and in thicknefs from that of a hair to that of a hog's brittle. They ifl'ue out of the fhell in that part where it naturally opens, and fix themfelves to any thing that lies in their way, to ftones, to fragments of fhells, or, which is the moft com- mon cafe, to the fhells of other Mufcles; whence it happens that there arc ufually fuch large parcels of Mufcles found to- gether. Thefe threads are expanded on every fide, and are ufually very numerous, an hundred and fifty having been found iffuing from one fhell; they ferve the office of fo many cables, and each pulling in its proper direction, they keep the Mu- fcle fixed againft any force that can be offered from whatever part it come. The filaments are well known to all who eat Mufcles, who ever carefully feparate them under the name of the beard; and Mr. Reaumur has found, that while the ani- mal is living in the fea, if they are all torn away by any acci- dent the creature has a power of fubftituting others in their room : He found that if a quantity of Mufcles were detached from one another and put into a veffel of any kind, and in that plunged into the fea, they in a little time there fattened themfelves both to the fides of the veffel and to one another's fhells; the extremity of each thread feemed in this cafe to ferve in the manner of a hand to feize upon any thing that it would fix to, and the other part which was flendercr and fmaller to do the office of an arm in conducting it. To know the manner of the Mufcle* s performing this operation, this diligent obferver put fome Mufcles into a veffel in his cham- ber, and covered them with fea-water; he there faw that they foon began to open their fhells, and each put forth that little body before defcribed by its refemblance to a tongue, and at the root of which thefe threads grow; they extended and fhort- ned this part feveral times, and thruft it out every way, often giving It not lefs than two inches in length, and trying before, behind, and on every fide with it, what were the proper places to fix their threads at : At the end of thefe trials they let it remain fixed for fome time on the fpot which they chofe for that purpofe, and then drawing it back into the fhell with great quicknefs, it was eafy to fee that they were 1 then fattened by one of thefe threads to the fpot where it had before touched and remained fixed for a few minutes; and in repeating this workmanfhip the threads are increafed in number one at every time, and being fixed in different places they fuftain the fifh at reft againft any common force.

The feveral threads were found to be very different from one another, the new formed ones being ever whiter, moregloffy, and more tranfparent than the others; and it appeared on a clofe examination, that it was not as might have been moft naturally fuppofed, the office of the tongue to convey the old threads one by one to the new places where they were now to be fixed, but that thefe in reality were now become ufe- lefs; and that every thread we fee now formed, is a new one made at this time; and in fine, that nature has given to fome fea-fifhes, as well as to many land-infects, a power of fpinning thefe threads for their neceffary ufes. And that Mufcles and the like fifh are under water, what caterpillars and fpiders are at land. To be well affured of this, however, Mr. Reaumur cut off all the beard or old threads of a Mufcle as -clofe as he could, without injuring the part, and the proof of the opinion of their fpinning new ones at pleafure was now brought to this eafy trial, whether thefe Mufcles fo deprived of their old ones could fix themfelves as foon as others which were pofTeffed of theirs, and could throw out their threads to as confiderable diftances. The experiment proved the truth of the conjecture, for thofe whofe beards or old threads were cut off, fixed themfelves as foon as thofe in which they were left, and fpread their threads to as great a diftance every way.

When the mecbanifm of this manufacture was thus far under- ftood, it became a natural defire to enquire into the nature of the part by which it was performed : This has hitherto been mentioned under the name of the tongue, from its fhape; but it is truly the arm of the fifh, and whenever it happens to be loofencd from its company, or fixed in a wrong place, it ferves the animal to drag its whole body fhell and all along, and to perform its feveral motions. It fixes itfelf to fome folid body, and then ftrongly contracting its length, the whole fifh mutt necefiarily follow it, and be pulled toward the place where it is fixed, This is an ufe however that this part is fo rarely put to, that it is not properly to be eftecmed a leg or an arm, for this j but, according to its more frequent employment, may much better be denominated the organ by which the threads are fpun.

Though this body is flat in the manner of a tongue for the greater part of its length, it is however rounded or cylindric about the bafe or infertion, and it is much fmaller there than in any other part; there are feveral mufcular ligaments faft- ned to it about the root or bafe, which hold it firmly againft the middle of the back of the fhell; of thefe ligaments there are four, which are particularly obfervable, and which ferve to move the body in any direction. There runs all along this body a flit or crack, which pierces very deeply into its fub- ftance,