315(5 
Bulletin //, United States National Museum. 
rarely absent. Fully grown males are scarce, a large catch consisting 
mostly of females ami young. 
Xiphophoriis monteziivue in distinguished from the other known species 
of the genus by having 7 anal rays, the scales with conspicuous dark 
edges, .a largo brown caudal spot, and the caudal appendage not sword- 
shaped, but with its end enlarged and blunt. (Jordan Sc Snyder.) 
Known only from IJio Verde, near Kascon, San Luis Potosi, Mexico. 
(Ty])e, a male. No. 6145, L. S. Jr. Univ. Mus. Coll. J. O. Snyder.) 
Xiphophorus montezumce, Jordan’ &, Sxydek, bull. U. S. Fish Com. 1809 (1900), 131, 
Rio Verde, near Rascon, Mexico. 
Page 702. The receiit studies of the eyes of American blind fishes by 
Dr. C. H. Eigeumann have shown that the species occurring in the caves 
of southwestern Missouri which has usually been identified as Typhlichthys 
siibterraneus, Girard, but which Dr. Eigenmann described as a new species 
under the name Typhliehthys rosw (p. 2835), has had an ancestrj’ quite 
distinct from that of TyphUchthys. It therefore is generically distinct 
from Typhllchlhys, and has been made the type of the new genus Troylich- 
ihys by Eigenmann. 
322 (a). TROGLICHTHYS, Eigenmann. 
Troglichthys, Eigexmaxn, Science, 'S'. S., Vol. ix, Xo. 217, j). 282, Fel». 24, 1809 (rosce). 
Scleral cartilages present, pigment in the pigment epithelium ; vitreal 
cavity obliterated, no hyaloid membrane; pupil closed, some of the eye 
muscles developed; no outer reticular layer; outer and inner nuclear 
layers merged into one; eye in adult not connected with the brain; pig- 
ment epithelium developed on the distal face of the eye, rarely over the 
sides and back; no cones; nuclear layers mere vestiges ; ganglionic layer 
restricted to the anterior face of the eye just within the pigmente*! 
epithelium. Maximum diameter of eye about 8.5//. No ventral fins. 
{TpebyX?/, cavern; fish.) 
The genera an I species of Amblyopsidrc may be determined by the fol- 
lowing key (from Eigenmann based largely on the character of the eyes: 
a. Titreou.-i body ami lens normal, the eye functional; no scleral cartilages; eye perma- 
nently connected with the brain by the optic nerve ; eye muscles normal ; no 
optic fiber layer. Minimum diameter of the e 5 ’e O.ToOji. Xo ventral tins. 
Cholooasteb, 321. 
b. Eye in adult more than 1 mm. in longitudinal diameter; lens over 0.5 mm. in diam- 
eter; retina very simple, it.s maximum thickness 83..5^i in the old; the outer 
and inner nuclear layers consisting of a single series of cells each ; the gaii 
glionic layer of isolated cells. ^laximum thickness of the outer nuclear 
layer 5/a, of the inner nuclear laj-er 8,a. corxl’TI'S, 1044. 
hi. Eye in adult less than 1 mm. in longitudinal diameter; lens less than 4 mm.; 
outer nuclear layer composed of at least 2 layers of cells; inner nuclear 
l.ayer of at least 3 layers of cells, the former at least lO/i thick, the latt<T at 
least 18/x. 
c. I’igment epithelium 65, a thick in the middle-age<l, 102a in the old. 
PAPILLIFEKUS, 1046. 
ec. I’igment 49a thick in the middle-aged, 74a in the old; 24 to 30 j>er cent thinner 
than in pa]>illiferus ; eye smaller. aga.ssif.ii, 1045. 
