22O 



RICHARDSON 



men tapers gradually to a broadly rounded extremity, which is slightly 

 excavate in the median line. 



The seven pairs of legs are but sparingly furnished with hairs. The 

 upper half of the opercular valve is black, the lower half yellow. 



There are three longitudinal lines of low swellings on the body, one 

 median, the other two placed one on either side of the median line. 



Only one specimen was taken at Lands End, 

 California, by Dr. Ritter and party. 



This species is closely allied to Synidotea con- 

 solidata (Stimpson), 1 but differs from that species 

 in the shape and greater size of the tubercles in 

 front of the eyes, the tubercles being hook-shaped 

 and very prominent in S. ritteri and projecting 

 far in front of the anterior margin of the head, 

 while in S. consolidata they are small (Stimpson 

 speaks of them as being minute), are not hooked, 

 and do not project any considerable distance in 

 front of the anterior margin of the head ; in the 

 greater size of the two median tubercles on the 

 anterior division of the head (Stimpson does not 

 mention these tubercles in his description, but in 

 the specimens sent to the U. S. National Mu- 

 S P . nov. (x 10). seum f rom Pacific Grove, California, by Mr. J. 



O. Snyder, and which Dr. James E. Benedict has identified with S. con- 

 solidata and figured in his paper on the genus Synidotea^ these tuber- 

 cles are present, but 

 very minute); in the 

 shape of the terminal 

 segment of the body, it 

 being much broader, 

 and tapering very grad- 

 ually to a broadly 

 rounded extremity, 

 which has a slight me- 

 dian notch or excavation 

 in S. ritferiy while in S. consolidata the terminal segment of the body is 

 narrower and tapers to an extremity marked by two pronounced teeth 

 or angulations separated by a deep median notch. 



Specimens of the same size were taken in making the above comparisons. 



IProc. Calif. Acad. Sci., I, p. 97, 1856; Bost. Jour. Nat. Hist., VI, p. 503, 1857. 

 2 Proc. Acad. Nat. Sci. Phila., p. 393, 1897. 



FIG. 101. a. Abdomen of Synidotea ritterisp. nov. (X 14). 

 b. Abdomen of Synidotea consolidata (Stimpson) (X 14)- 



