THE STOMATOPODA OF PORTO RICO. 
153 
carina on tto telson. Thin is so small a character by which to separate two species, otherwise 
apparently identical, that, one would he inclined to suspect that this might he a case of individual 
variation. But through the courtesy of Dr. Walter Faxon I have been able to examine the material 
in the Museum of Comparative Zoology at Harvard College and to compare specimens of G. cerstedii 
identified by Dr. Hansen with specimens from 18 localities on the Atlantic, besides those of the present 
collection, and with specimens of G. chirctgra from 16 localities in the Pacific and Indian oceans. I found 
that the difference pointed out by Hansen is perfectly constant. In every specimen of G. chiragrn from 
the Indo-Pacific region the valley between the intermediate marginal carina and the central prominences 
Fig. 2. Gonodaclylus cerstedii, Hansen, x 2; not 
accurately to scale. 
Fig. 3. Pseudosquilla ciliata, Miers, male, x 2; not 
accurately to scale. 
of the telson presented a smooth, even slope, without trace of additional carina. On the other hand, 
every specimen from the Atlantic region possessed the supplementary carina, somewhat variable in 
length and elevation, but always distinctly present. It may be well to note here that in order to see 
this feature, as well as the other sculpturings of the telson, distinctly, the surface must be dry. In a 
specimen freshly lifted from a bottle of alcohol and covered with the licpiid it is not easily visible. 
G. cerstedii is readily distinguished from G. spinosus Bigelow and G. spinosissimus Pfeffer by the 
absence of prickles on the dorsal surface; and it is separated from G. glabrous Brooks and G. graphurus 
Miers by the possession of only three central longitudinal carina; on the telson. There are small 
