HIPPOGLOSSINA VAGRANS. 221 
fifty fathoms or less, thus bringing themselves among the shoal-water forms. 
This will be made sufficiently clear by examination of the list with least and 
greatest depths. Glyptocephalus cynoglossus is a marked instance, ranging as 
it does from a depth of less than a hundred fathoms to one of more than 
eight hundred. 
That there was a comparatively recent connection between the Pacific 
and the Atlantic across the isthmus, and that separation of the two oceans 
affected the shoal water forms more recently than the forms of the deep 
sea is favored by the representatives of the Pleuronectide in this collection. 
Close affinities exist between the species of Citharichthys, Platophrys, Sym- 
phurus, and Monolene from opposite sides of the isthmus. These relation- 
ships are especially noticeable in the species of Symphurus and even more 
so in those of Monolene, JZ. maculipinna and M. sessilicauda, for instance. 
Type specimens of IZ. sessilicauda at hand have forty-five vertebrae, as in 
M. maculipinna, instead of forty-three as was originally stated in the generic 
diagnosis. 
In the “ Challenger” Report, published in 1887, Dr. Giinther gives a 
list of nineteen species of Pleuronectoids known to occur at depths greater 
than one hundred fathoms; the works of the “ Talisman,” the “ Albatross,” 
and the “ Investigator” have since increased the list so that it now contains 
fifty-five species. 
PLEURONECTID&. 
Hippoglossina vagrans var. n. 
D. 59-60; A. 44-47; V.6; P. 11 on each side; C. 17; Ll. 73-77; Ltr. 
21-22 + 23-26. 
Body sinistral, compressed, greatest depth near midway from snout to 
base of caudal about one third of the total length, profile outlines on dorsal 
and ventral edges curving regularly from the deepest portion forward to the 
eyes and backward to the caudal pedicel. Head two sevenths of the entire 
length, with a narrow sharp ridge separating the eyes, with a prominent 
angle below the symphysis of the lower jaws and another below the angular, 
and with a wide indentation in front of and encroached upon by the upper 
eye. Snout hardly three fifths as long as the eye, lower jaw longer. 
Mouth wide; maxilla with a low prominence anteriorly, reaching backward 
of the middle of the left eye. Nostrils small, left pair in front of the inter- 
