52 University of California Publications in Zoology [VoL 23 
2. Rostrum short, not reaching beyond middle of antennal scale. 
a. Rostrum not reaching as far as cornea. (Not known north of 
San Francisco Bay.) PE 67 
aylori, p. 67. 
b. Rostrum reaching as far as or beyond the cornea. 
i. Rostrum not reaching second segment of antennular peduncle. 
a. Antennal scale about equal in length to or shorter than 
the telson. (Not known south of San Francisco Bay.) 
brevirostris, p. 66. 
b. Antennal scale longer than the telson. (Not known north 
of San Francisco Bay.) 
palpator, p. 65. 
ii. Rostrum reaching second segment of antennular peduncle and 
usually beyond. 
syria cristata, p. 69. 
As can be seen above, the species of Spirontocaris dealt with in this paper 
arrange themselves readily into four groups based on the number of supraorbital 
spines; the last of these groups has been subdivided for convenience, owing to 
the number of species included in it. 
I. Group with more than two supraorbital spines, p. 52. 
II. Group with two supraorbital spines, p. 53. 
III. Group with one supraorbital spine, p. 55. 
IV. Group with no supraorbital spines. 
a. Rostrum as long as or longer than remainder of carapace, p. 58. 
b. Rostrum shorter than remainder of carapace, p. 65. 
I. Group with more than two supraorbital spines. 
Pp vi 
Spirontocaris prionota (Stimpson) 
Hippolyte prionota Stimpson, Proc. Acad. Nat. Sci. Phila., 16, 153, 1864; 
Kingsley, Bull.’ Essex Inst., 14, 127, pl. 2, fig. 9, 1883. 
Spirontocaris prionota Walker, Trans. Liverpool Biol. Soc., 12, 277, 1898; 
Holmes (mis-spelled prionata), Occas. Papers Calif. Acad. Sci., 7, 206, 
1900; Rathbun, H. A. E., 10, 61, 1904. 
Fig. 28. Spirontocaris prionota, lateral view of carapace and abdomen 
(adapted from Kingsley). 
Characters.—Carapace with two or three supraorbital spines in a longitudinal 
series; dorsally crested nearly to the posterior margin and armed with three 
teeth, the anterior margins of which are armed on either side with a short, trans- 
verse row of small spines. Rostrum shorter than the carapace, lamelliform, very 
deep though not so deep as long; general outline roughly subcireular; anterior 
—— 
