Page:The American Cyclopædia (1879) Volume II.djvu/743

 BLINDWORM 723 is without scales as far as the pectoral fins, the rest of the body having small ones ; the sides of the head are provided with numerous trans- verse and longitudinal ridges, each having 20 to 30 papillas, cup-shaped at the top and with a delicate tactile filament freely supplied with nerves from the 5th pair ; there are also on the sides, from the pectoral to the tail, about 10 vertical ridges, with the papilla less well defined ; the naked skin is of extreme delicacy. The optic lobes of the brain are as well de- veloped as in ordinary fishes, and rudimentary eyes have been found under the skin by Prof. J. Wyman and others. The eyes have the membranes, pigment, and lens, and, though imperfect, are constructed after the vertebrate type. They cannot form an image, as the in- tegument and areolar tissue over them would prevent the transmission of any but very dif- fused light ; no pupil or undoubted iris has been found. The organ of hearing is largely developed. The vent is in advance of the pectorals. They are probably distributed in all the subterranean rivers flowing through the limestone region under the carboniferous rocks of the central United States; they have often been taken from wells. Another color- less blind fish (typhlichthys subterraneus, Gi- ; rard), 1J to 2 inches long and having no ven- tral fins, has been found in the Mammoth cave, and in the central and southern portion of the subterranean region. In the genus cho- logaster (Ag.) are found all the family charac- ters of the above two blind species, but it has eyes, a brownish color, and no papillary ridges on the head and body ; yet it is a subterranean fish in some instances. In the Cuban blind fishes (genera lucifuga and stygieola), de- scribed by Prof. Poey, there are ciliary appen- dages on the head and body, well developed as organs of touch, but without the tactile barbels on the jaws usually found in the cod group, to which these fishes are nearly allied ; the optic lobes are large, and the eyes exist, but so im- bedded in the flesh of the head as to be use- less; the body, cheeks, and opercular bones are covered with scales. Though they resemble amblyopsis, it will be seen that they belong to a marine family, though now found in fresh water in caves, and are far removed from the latter. From the facts here enumerated, and many others that may be found in the "Amer- ican Naturalist," vol. vi., pp. 6-30, for Jan- uary, 1872, Mr. F. W. Putnam expresses the opinion that these fishes have always been blind, and have not become so from living in darkness. As far as known, the young of blind fishes have no external eyes when born. KM M> Vt'Olt >1 (anguis fragilis. Linn.), a rep- : tile of the order of saurians and family of scin- | coids, or lepiilo-sauri. It is neither a worm, | nor is it blind. The family is extremely inter- esting, as it serves to establish a gradation be- , tween the true saurians and the serpents by means of the genus anguis and others nearly allied to it, in which the body becomes elon- gated and serpentiform, the ribs increase in number, and the limbs cease to appear exter- nally, being quite rudimentary. We see a sim- BUndwunii (Anguia fragilis). ilar approach to the ophidians in some of the cyclosaurians, as in the amphisbwna, which is properly a saurian. These intermediate forms were placed by Gray in his order of saurophi- dians ; while Merrem, being unable to draw the line between ophidians and saurians, united them into the single order squamata. The body and tail of the blindworm are cylindrical and snake-like, the latter being as long as the former, and even longer ; the head, triangular and rounded in front, is covered by 11 large and several smaller plates ; the nostrils are lat- eral, each opening in the centre of the nasal plates; the tongue is free, flat, not retractile into a sheath, divided slightly at the end, but not forked like that of the serpent, its surface partly granular and partly velvety ; the palate is not toothed ; the jaw teeth are small, sharp, and inclined backward. The bones of the head are not movable as in serpents, and the jaws are short and united firmly at the symphysis, so that the opening of the mouth is always the same, contrasting strongly with the great mo- bility and extensibility of those parts in ophidi- ans. The genus anguis, and its allied genera, also approach the saurians, and differ from the serpents, in having two eyelids, moving ver- tically, and capable of entirely covering the eye, the lower one provided with scales. The external auditory foramen is distinct, though small and linear ; there are no legs, but the rudiments of the shoulder, sternum, and pelvis are found in the substance of the muscles, while in the snakes they are reduced to a mere vestige of a posterior extremity. The scales are six-sided, except on the sides where they are rhomboid, smooth, imbricated, or fish- like, and nearly of the same size above and be- neath. One lung is much more developed than the other, as in serpents; the opening of the cloaca is transverse. The blindworm is found in Europe, from Russia and Sweden to the Mediterranean, and also in northern Africa; it forms now the only species of the genus anguis,