52 University of California Publications in Zoology [Vol. 23 



2. Eostrum short, not reaching beyond middle of antennal scale. 



a. Eostrum not reaching as far as cornea. (Not known north of 



San Francisco Bay.) 



taylori, p. 67. 



b. Eostrum reaching as far as or beyond the cornea. 



i. Eostrum 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. Eostrum reaching second segment of antennular peduncle and 



usually beyond. 



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. Eostrum as long as or longer than remainder of carapace, p. 58. 



b. Eostrum shorter than remainder of carapace, p. 65. 



I. Group with more tlian two supraorbital spines. 



Spirontocaris prionota (Stimpson) 



HippoJyte prionota Stimpson, Proc. Acad. Nat. Sei. Phila., 16, 153, 1864; 



Kingsley, Bull. Essex Inst., 14, 127, pi. 2, fig. 9, 1883. 

 Spirontocaris prionota Walker, Trans. Liverpool Biol. Soc, 12, 277, 1898; 



Holmes (mis-spelled prionata), Occas. Papers Calif. Acad. Sei., 7, 206, 



1900; Eathbun, 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. Eostrum shorter than the carapace, lamelliform, very 

 deep though not so deep as long; general outline roughly subeircular; anterior 



