206 CALIFORNIA ACADEMY OF SCIENCES. 



Genus Spirontocaris Bate. 

 t 



Carapace anteriorly carinated and produced into a deep, laterally com- 

 pressed rostrum which is serrated ou both margins. There are two or 

 more supraorbital spines, an autennal spine, and a spine at the antero- 

 inferior angle of the carapace. First and second antennae much as in 

 Hippolyte. Mandibles with a broad molar process, a slender apical process, 

 and a small, two jointed palp. Third maxillipeds furnished with a small 

 exognath and having the tip of the last joint armed with spinules. First 

 pair of pereopods short, robust; second pair slender, the carpus seven- 

 jointed. Posterior pereopods subequal, similar, and furnished with biun- 

 guiculate dactyls which are spinulous below. 



Type. S. spinus (SOWERBY). 



Spirontocaris prionata (St.). 



Hippolyte prionata SIIMPSON, Proc. Acad. Nat. Sci. Phila., 1864, p. 153. 



KINGSLEY, Bull. Essex Inst., Vol. XIV, 1883, p. 127, PI. II, fig. 9. 



SHARP, Proc. Acad. Nat. Sci. Phila., 1893, p. 117. 

 Spirontocaris prionata WALKER, Trans. Liverpool Biol. Soc., Vol. XII, 



1898, p. 277. 



Carapace large, the anterior margin furnished with two spines, of which 

 the upper one is the larger. There are two or three supraorbital spines in 

 a longitudinal series; the upper side is crested nearly to the posterior 

 margin and cut into three large teeth whose transverse anterior margins are 

 armed on either side with several small spines. Rostrum very broad, widest 

 a little behind the tip, the upper margin thickly set with small spines, 

 while the lower margin is furnished with four or five larger spines. An- 

 teunules short, the external basal spine large, reaching about to the tip of 

 the peduncle; the first joint of the peduncle is longer than the next two 

 and has a spine at the antero-external angle; second joint with a large 

 spine on the outer side; third joint with a slender spine above the articu- 

 lation of the larger flagellum and a similar spine near the articulation of 

 the slender one; thick flagellum longer than the slender one, with a slen- 

 der tip about one-third the length of the proximal portion. Antennae 

 somewhat shorter than the body; acicle subtriaugular, about reaching the 

 tip of the rostrum; peduncle not reaching the middle of the acicle. Man- 

 dibles stout, cutting edge long, slender, distally four-toothed, and slightly 

 longer than the palp; palp two-jointed, the last joint narrow and about 

 twice as long as the first. Maxillipeds very stout and exceeding the tip of 

 the rostrum, the last two joints bent downwards; the antepenultimate 

 joint is somewhat widened at the tip where it bears, on the upper side, two 

 small prominences, each of which bears a spine and numerous setaa; last 

 joint over twice the length of the preceding one, the tip armed with a 

 circle of dark-colored spines; exopod small, scarcely reaching the tip of 



