BLIND SPOT. 180 BLINDWORM. suspect that their development has been influ- enced, in each eye, by the normal space-values of the corresponding area of the other eye. Bibliography. H. von llelmholtz, Physiolo- gische Optik (Hamburg, 1890) ; Titehener, Ex- perimental Psychology (New York, 1901); Wundt, Physiologische Psychologic (Leipzig, 1893). BLINDSTORY. A story or other architec- tural horizipntul division in a building, either out- side or inside, which is without windows or other openings of importance. On the outside, it may consist of a blank wall or of a series of blind arcades. On the inside of churches the term is applied especially to the middle story of the nave above the side-aisles and below the clearstory (q.v. ). or windowed story, of which it is the opposite in architectural terminology. It is then intercliangeable with triforiiim (q.v.) ; and is in the form of a wide, open gallery in Byzantine, Lombard, Norman, and other Romanesque schools. In Gothic this gallery is gradually reduced until it becomes a series of false arcades. BLIND TOM (c. 18.50—) . A musical prodigy, a blind and almost idiotic negro, born of slave parents near Columbus, Ga., and called Thomas Bethune after his master. His musical genius attnicted wide attention, and from 1861 he was frequently exhibited in New York. He was able, after a single hearing, to reiuler even complicated music on the piano, frequently playing two melo- dies simultaneously. After plaj-ing, he often sprang up and applauded himself vociferously, lie was dilUcult to manage, and his growing men- tal infirmity caused his final withdrawal, since which he is said to have lived in obscurity in New Y'ork. BLINDWOEM (Dan. blindorm; so called on account of the small size of the eyes), or Blind Snake. A name given to certain worm-sluiped, burrowing reptiles and amphibians. It applies especially to those of three groups, none of which is really blind : ( 1 ) The serpent-like lizards of the family An- guidie, of which the common blindworm, orvet, or slow- worm (Anguis fragilis) of Europe and western Asia is a type. Both the body and tail are elongated and serpent-like, and rarely more than one foot long; it possesses no external traces of appendages, but has internally a rudimentary shoulder-girdle, sternum, and pelvis, placing it intermediate between the lizards, which have four legs, and the snakes, in which all traces of limbs are lost; indeed, it has been proposed to put several snake like lizards, with more or less de- generate legs, together with some of their allies, into one group and call them serpent-lizards (Sauropliida) . The eyes are bright, l)ut snuill, giving rise to the belief that the animal is lilind. It feeds on slugs and insects, and is perfectly harmless. It is so very timid that when startled its muscles contract violently, and the body is rendered so stiff and brittle that it is easily bro- ken. Blindworms l)ring fortli their young alive, and winter together in numbers under brish and leaves, or in loose, dry soil. Several genera of the same family, and presenting similar charac- teristics, inhabit the warmer parts of .merica, some of which have i)art or all of tlicir limbs externally developed; the beautiful giecn, brown- banded, many-keeled lizard (Girrhonotus inulti- carinatus) of California is an example. Best known, however, is the 'glass-snake,' fre- quently found in the loose soil of dry fields from Illinois to Florida, and westward into Mexico. It has no feet, but by serpentine movements is able to move with considerable swiftness; and when overtaken can luirdly be captured without injury, for its tail is so loosely articulated and so free of muscles that it breaks off like a bit of glass, to be quickly renewed by a new growth if the animal is not further harmed. It is yellow- ish-green above, with black lines. "The snout is long and pointed, the ear-pits large, the eyelids well developed, and each flank is provided with
- 'GLA88-8NAKE" lizard.
a, top of Iiead : b, side of tiead. what is ordinarily a deep groove, but which, on the animal's swallowing some large object, ap- pears as a tract of elastic skin, the rigid skin of the body generally being incapable of expan- sion." It is perfectly harmless. Its technical name is Ophisauriis vcntrulis. Consult Cope, (■rocodilians, Lizards, and i^nakes (Smithsonian Institution, Washington, 1900). (2) A family of true serpents (Typhlopidte) , called 'blind snakes,' because their eyes in all cases are minute and weak, and in some are almost invisible under overlapping plates. They rank lowest among serpents, are only a few inches in length, and have rigid bodies suitable for burrowing, shaped much like those of earth- worms, and with curved tails. They occur in all the warmer parts of the world, boring their way through the loose top-soil and feeding on worms, grubs, and insects; and in India some- times appear in large numbers above ground after showers, inspiring the natives with foolish dread, for they are ([uite harmless. Xumeroug genera and species inluibit the warmer parts of America. Consult Gosse, A Xuturalist's Sojourn in ■Jamaica (London, 1851). (3) The Ca'ciliida'. a family of degenerate uro- delous ampliibians for a Umg time classed among reptiles. The body is vermiform and without limbs, all traces even of the pelvic and pectoral girdles having been lost. The ribs are too short to encircle the body, and the vertcbrie are articu- lated as in fishes and lower amphibia, and not as in snakes. There are small scales in the skin, the eyes are very snuUl, and in some species are cov- ered entirely by the skin. There is neither tym- panic membrane nor tympanic cavity. The small mouth lies on the ventral side of the conieal liead, and there is no tail, for the vent opens at the posterior end of the bod}'. All these dejiartures from the typical amphibian type are adaptive, fitting the ciecilians for their subterranean bur- rowing life. The young are hatched with exter- nal gills, and gill-slits, and for a time lead an acjuatic life. The c;reili;>ns inhabit warm coun- tries and feed on c.irllnvcirms and inscctlarvie; they are most abundant in South America, and Mexico and Ceylon possess several species. Some- times they are called blindworms, but these am-
