ISOPODS OF NORTH AMERICA. 



379 



expansion, so that the}' secni more dorsal in position. The tirst anten- 

 nffi have the basal article not enlarg'ed; the second is about equal in 

 length to the tirst; the third and fourth are sube(jual, and each is al)Out 

 one and a half times lonoer than the third. The tirst pair of anteniue 

 extend to the end of the fourth peduncular article of the second pair 



of antenna'. The basal article of the 

 second pair of antennie is almost in- 

 conspicuous from a dorsal view; 

 the second article is short; the third, 

 fourth, and fifth are protji^ressivelv 

 longer, each being one and a half 

 times longer than the preceding arti- 

 cle. The flagel- 

 lura consists of ten 

 articles. W h e n 

 retracted, the sec- 

 ond antennae ex- 

 tend to the poste- 

 rior margin of the 

 third thoracic seg- 

 ment. The maxil- 

 lipeds have a ))alp 

 of three articles. 



The first four 

 segments of the 

 thorax are longer than the last three. The epimera of all the seg- 

 ments are firmly united with the segments. Three longitudinal rows 

 of tubercles, one" median and two lateral, extend the entire length 

 of the thorax. The tubercles in the lateral rows are more pronounced. 

 In a transverse line the tubercles are arranged three on each seg- 

 ment. 



The abdomen is composed of a single segment with lateral sutures 

 at the base indicating another partly coalesced segment; it is elongate 

 with the posterior extremity rounded. There is a very slight indica- 

 tion of a median excavation at the posterior end. 

 The legs are more or less similar in structure. 



Fig. 412.— Synidotea pallida (After Bene- 

 dict). X 2i. 



Fig. 413.— Synidotea 



PALLIDA. MaXIL- 

 LIPED. X 27i. 



SYNIDOTEA EROSA Benedict. 



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

 Richardson, Proc. U. S. Nat. Mus., XXI, ]899, p. 848; Ann. Mag. Nat. 

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



Locality. — Sannakh Island, Alaska. 



Depth. — 483 fathoms. 



Bod}' oblong-ovate, three times longer than wide, 7 mm. : 21 mm. 



