386 



BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



separation on the fir.st four segments. On the last three segments, 

 however, there is a faint line indicating this. The lateral margins of 

 the segments are straight. 



The seo-uients of the abdomen are all coalesced to form one large 

 terminal segment. At the base of this segment is a suture line on 

 either side, indicating another partly coalesced segment. The terminal 

 segment is triangulate, with apex excavate, forming two blunt teeth 

 or angles. 



The legs are more or less similar in structure. 



SYNIDOTEA LATICAUDA Benedict. 



Synidotea kUicmtda Benedict, Proc. Acad. Nat. Sci. Phila., 1897, pp. .39.3-394.— 

 Richardson, Proc. U. S. Nat. Mus., XXI, 1899, p. 849; Ann. Mag. Nat. 

 Hist. (7), IV, 1899, p. 268; American Naturalist, XXXIV, 1900, p. 228. 



Locality. — San Francisco Bay. 



Body oblong-ovate, a little more than two and a half times longer 

 than wide; Ti mm. : 17i mm. 



Head wider than long; 2i mm. :J: mm., with the anterior margin 

 almost straight. Eyes small, round, composite, and situated at the 



sides of the head. The tirst pair of an- 

 tenna have the tirst three articles short 

 and sul)e(|ual. The fourth article is two 

 and a half times longer than anj^ of the 

 preceding ones. The first antenna? ex- 

 tend to the end of the third article of the 

 peduncle of the second antenna?. The 

 first two articles of the second antennae 

 are subequal; the third and fourth are 

 subequal, a n d each is 

 about twice as long as the 

 second; the fifth article is 

 one and a half times 

 longer than the fourth. 

 The flagellum is composed 

 of seventeen articles. 

 When retracted the second antennt\? extend to the pos- 

 terior margin of the fifth thoracic segment. The 

 maxillipeds have a palp composed of three articles. 



The first, fifth, sixth, and seventh segments of the 

 thorax are subequal in length. The second, third, 

 and fourth are subequal and are longer tlian the others, each 

 being one-half millimeter longer than either the first, fifth, sixth, 

 or seventh segments. The epimera of all the segments are perfectly 

 and firmly coalesced with the segments, with no indication of a sepa- 

 ration. 



Fig. 425.— Synidotea laticauda 

 (After Benedict), x 2^. 



Fig. 426.— Synido- 

 tea LATICAUDA. 



Maxilliped. X 

 15f. 



