Page:1902 Encyclopædia Britannica - Volume 25 - A-AUS.pdf/592

 542

ARACHNIDA

Intromittent organ of male lodged on the dorsal side of the Its ventral surface provided with one prosternal, two meso- 1st(?pair of prosomatic appendages.) sternal, and one metasternal plate. Appendages of 1st pair conFamilies — Hexisopodidae (Jlexisopus). Solpugidae (Solpuga, sisting of three segments, completely chelate, without poison Rhagodes). Galeodidae (Galeodes). aland ; of 2nd pair slender, leg-like, tipped with three claws, the

Fig. 66.—Galeodes, sp., one of the Solifugae. Ventral view to show legs and somites. I to VI, the six leghearing somites of the prosoma; apisth. 1, first or genital' somite of the opisthosoma ; ge, site of the genital aperture ; st, thoracic tracheal aperture ; I'2, anterior tracheal aperture of the opisthosoma in somite 2 of thes opisthosoma ; I, tracheal aperture in somite 3 of the opisthosoma; a, anus. (From Lankester, “Limulus an Arachnid.”)

Fig. 65.—Kcenenia mimbilis, Grassi, one of the Palpigradi. A, ventral view of prosoma and of anterior region of opisthosoma with the appendages cut off near the base; a and 6, prosternites ; c, mesosternite ; and d, metasternite of the prosoma; ./, ventral surface of the prai-genital somite; g, sternite of the genital somite (first opisthosomatic somite). B, dorsal view. I to VI, prosomatic appendages ; 1 opisth, genital somite (first opisthosomatic somite). C, lateral view. I to VI, prosomatic appendages; a, o, c, the three tergal plates of the prosoma; prm-gen, the pnc-genital somite ; 1 to 10, the ten somites of the opisthosoma. D, chelicera. (Original drawing by Pocock and Pickard-Cambridge, after Hansen and Sorensen.) basal segment without sterno-coxal process taking no share in mastication, and widely separated from its fellow of the opposite side ; 3rd, 4th, 5th, and 6th appendages similar in form to the 2nd and to each other. Proboscis free, not supported from below by either the prosternum or the basal segments of the appendages of the 2nd pair. Opisthosoma consisting of only ten somites, which have no tergal and sternal elements, the prse-genital somite contracted to form a “waist,” as in the Pedipalpi; the last three narrowed to form a caudal support for the many-jointed flagelliform telson, as in the Urotricha. Respiratory organs atrophied. Family—Kceneniidse (Kcenenia). Remarks. — An extremely remarkable minute form originally described by Grassi (34) from Sicily, and since further described by Hansen (35). Recently the genus has been found in Texas, U.S.A. Only one genus of the order is known. Order 5. Solifugae = Mycetophorae (see Figs. 66 to 69).—Dorsal area of prosoma covered with three distinct plates, two smaller representing the terga of the 5th and 6th somites, and a larger representing those of the anterior four somites, although the Fig. 6$.—Galeodes, sp., one of the Fig. 67.—Galeodes, sp., one of the reduced terga. of the 3rd and 4th are traceable behind the larger Solifugse. Dorsal view. 1 to Solifugaa. Ventral view with plate. The latter bears a pair of median eyes and obsolete lateral VI, bases of the prosomatic the appendages cut off at the appendages ; o, eyes ; a, lateral eyes on each side. Sternal elements of prosoma almost entirely base. I to VI, prosomatic region of the cephalic plate to appendages ; s, prosomatic absent, traces of a prosternum and metasternum alone remaining. which the first pair of appendstigma or aperture of the Rostrum free, not supported by either the prosternum or the basal ages are articulated ; b, cephalic tracheal system; 1, first opissegments of the appendages. Appendages of 1st pair large, plate with median eye; c, dorthosomatic sternite covering sal element of somites bearing chelate, bisegmented, articulated to the sides of the head-shield ; the genital aperture g; 2, third and fourth pairs of apsecond opisthosomatic sternite appendages of 2nd pair simple, pediform, with protrusible (? suctorial) pendages ; d, second plate of covering the second pair of organ, and no claws at the tip ; their basal segments united in the prosoma with fifth pair of tracheal apertures spl; sp2, the appendages; e, third or hinderthe middle line and furnished with sterno-coxal process. Remainthird pair of tracheal apertures; most plate of the prosoma ing pairs of appendages with their basal segments immovably fixed 10, the tenth opisthosomatic beneath which the sixth pair somite an, the anal aperture. to the sternal surface, similar in form, the posterior three pairs of legs is articulated; 1, 2, (Original by Pickard-Cambridge furnished with two claws supported on long stalks ; the basal 9, 10, first, second, ninth, and Pocock.) and tenth somites of the segments of the 6th pair bearing five pairs of tactile sensory organs opisthosoma ; an, anus. (Orior malleoli. The pne-genital somite is suppressed. Opisthosoma ginal.) composed of ten somites. Respiratory organs tracheal, opening upon the ventral surface of the 2nd and 3rd, and sometimes also Remarks. — These most strange - looking Arachnids occur in of the 4th somite of the opisthosoma. A supplementary pair of tracheae opening behind the basal segment of the 4th appendage of warmer temperate, and tropical regions of Asia, Africa, and America. Their anatomy has not been studied, as yet, by means of freshlythe prosoma.