of the Pacific Shores of North America. 497 
inal segment exhibits a rather sharp ridge along the dorsal 
edge, which is not perceptible in C. vulgaris. These differ- 
ences are indeed very slight, but they are nevertheless con- 
stant, and taken together with the remoteness of the 
geographical limits of the two forms, they seem to indicate 
with certainty a specific diversity. 
The color of our species is a very dark gray, or blackish, 
becoming entirely black at the tail. Hands tinted with 
lilac. The hand (see figure) is very different from that of 
C. Franciscorum, but even without reference to this char- 
acter, the black tail will enable any one readily to pick out 
specimens of this species from the heaps of the common 
kind which may be seen on every fish-stand in the market. 
C nigricauda is much less abundant in San Francisco 
Bay than the preceding species, and is found in deeper 
Water. It occurs in Puget Sound, (Exploring Expedition ;) 
at the mouth of the Columbia, ('Trowbridge;) Tomales 
Bay, (Samuels ;) and at Monterey, (Capt. Beechey.) 
Mus. Bost. Soc.; Phil. Acad.; Smithsonian; Expl Ex- 
. Ped.; Paris; Acad. Petrop.; R. C. S.; Zoól. Soc. 
CRANGON MUNITUS. Dana. 
Crangon munitus, Daxa ; U. S. Exploring Expedition, Orust. i. 536. Pl. XXXIII. 
f. 5. 
Remarkable for the four strong spines with which its 
carapax is armed on the superior surface. 
Hab. Puget Sound, (Expl. Exped.) 
Mus. Expl. Exped. 
PARACRANGON ECHINATUS. Dana. 
Paracrangon echinatus, Dana; U.S. Exploring Expedition, Crust. i. 538. 
PI. XXXIII f. 6. 
With the hands of a Crangon this species resembles 
JOURNAL B. S. N. H. 64 
