378 BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



but differ.s from that species in the shape and greater size of the 

 tubercles in front of the eyes, the tuljercles being- hook-shaped and 

 ver}' prominent in /S. riUeri and projecting far in front of the anterior 

 margin of the head, while in S. consoJidata the}' are small (iStimpson 

 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 descrip- 

 tion, but in the specimens sent to the U. S. National Museum from 

 ^ jj Pacific Grove, California, by Mr, J. (). 



Snyder, and which Dr. James E. Bene- 

 dict has identitied with S. cnnsolidafa 

 and figured in his paper on the genus 

 Synidotea,"' these tubercles are pres- 

 ent, but very minute; they do not 



FIG. 411.-,,, ABDOMEN OF SYNIDOTEA R.T- ovcrhaug thcfroutal emargination); 

 TERi. h, Abdomen of Synidotea con- in the shape of the terminal segment 



of the body, it ]>eing much broader, 

 and tapering very gradually to a broadly rounded extremit}', which 

 has a slight median notch or excavation in S. rltterl, while in S. co7i- 

 KoJidatd the terminal segment of the bod}^ is narrower and tapers to an 

 extremit}' marked by two pronounced teeth or angulations separated 

 f)y a deep median notch. 



Specimens of the same size were taken in making the above com- 

 parisons. 



This species is named for Dr. William PI Ritter, of the University 

 of California, from whom the specimens were received. 



SYNIDOTEA PALLIDA Benedict. 



Synidotea pallida Benedict, Proc. Acad. Nat. Sci. Phila., 1897, pp. 396-397.— 

 Richardson, Proc. U. S. Nat. Mus., XXI, 1899, p. 848; Ann. Mag. Nat. 

 Hist. (7), IV, 1899, p. 268; American Naturalist, XXXIV, 1900, p. 227. 



Locality. — Chirikof Island, Alaska. 



DepfL^em fathoms. 



Body narrow, elongate, about two and a half times longer than wide, 

 h nun.: 12 mm. Length of al)domen eijual to less than half the length 

 of the entir(> body, 5 nnn. : 12 mm. 



Head with the front excavate between the antero-lateral angles. The 

 sides of the heati are produced in a wide border, the extei'ior margin of 

 which is straight. There are four tubercles on the anterior portion of 

 the head, two in the center, one on either side of the median longitu- 

 dinal line, and two lateral to these, one in front of each eye. The 

 eyes are round and composite, and placed at the base of the lateral 



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



