94 
Pontophilus gracilis, S. I. Smith. 
Plate XXV. 
1882. Pontophilus gracilis, Smith, Bull. Mus. Comp. Zodl. 
Harvard, Vol. X., p. 36, Pl. 7, figs. 2-3a. 
1886. Pontophilus gracilis, Smith, Rep. U.S. Fish Comm., p. 50, 
Ph aa, fess i ora 
1891. Pontophilus gracilis, Wood-Mason and Alcock, Ann. Nat. 
Hist., Ser. 6, Vol. VILT., p. 36x. 
1895. Pontophilus gracilis, Ortmann, Proc. Acad. Philad., pp 
183, 186. 
1901. Pontophilus gracilis, Alcock, Catal. Indian Macrura, p. 
II5. 
Various authors have noted that the species which Bate 
established under the name P. gracilis in 1888 as a new species 
is in fact distinct from the earlier P. gracilis of Smith. Nearly 
at the same time in 1893, Ortmann renamed Bate’s species 
P. challengert and Faxon renamed it P. bater.* In comparing 
the figures and descriptions of the numerous species which have 
been assigned to the present genus the student will be struck 
with the perplexing minuteness of the characters by which 
many of the species have been discriminated. The view which 
Dr. Doflein has recently propoundedf as to the considerable 
variation which the eyes of deep-sea crustaceans undergo, 
according to their habitat as well as their age, will make oph- 
thalmic differences less serviceable than hitherto in classifica- 
‘ion. The value of other distinctive marks will, no doubt, 
have to be carefully weighed in the future. The specimen here 
under consideration agrees more closely with Professor Smith’s. 
species above named than with any other, although there are 
some small details to be noticed by which it might claim to be 
differentiated. 
The rostrum is sharp-pointed, not reaching beyond the eyes, 
with a-pair of denticles at about a third of its length from the 
base. On the under margin near the apex are some sete not 
mentioned in the original description. The medio-dorsal carina 
has two forward-pointing teeth, of which the hinder or cardiac 
one is fully as large as the front or gastric one, though in 
Smith’s figures it appears to be much smaller. On either side 
* Ortmann, Decap. und Schizop der Plankton-Exp., p. 49. Faxon, Mem. 
Mus. Comp. Zodl., Harvard, Vol. XVIII., p. 131. Faxon’s name, though 
slightly the earlier, had been anticipated by Kingsleys Crangon batet, a 
synonym of Ponlopliilus intermedius (Bate). 
+ Biol. Centralblatt, Vol. XXIIJ., No. 16 and 17, p. 570, 1903. 
