ISOPODS OF NORTH AMERICA. 393 



median lonoitudinal line of the thorax i.s a row of low tubercles, one 

 for each segment, which increase in size toward the posterior end of 

 the series. On eitlier side of this median tubercle is a oroup of low 

 tubercles on each sej>inent of the thorax, with six or more tul)ercles in 

 each group. 



The abdomen is composed of a single segment, with lateral sutures 

 indicative of another coalesced segment. At the base of the segment, 

 in line with the median row of tubercles on the thorax, are two 

 tubercles in longitudinal series. On either side of this series are low 

 rugosities. The al)domen is acutely pointed at the extremit}', becom- 

 ing more rapidly narrow from the middle of the segment. 



The legs are more or less similar in structure. 



62. Genus COLIDOTEA Richardson. 



Flagellum of second pair of antenniv multi-articulate. Epimera of 

 the four anterior thoracic segments coalesced and tirndy united with 

 the segments, there being no indication of a separation. Epimera of 

 last three segments of thorax distinctly separated from the segments. 

 Abdomen consisting of a single segment, with a suture line on either 

 side at the base indicating another partly coalesced segment. Maxilli- 

 peds with the palp composed of four" articles. 



COLIDOTEA ROSTRATA (Benedict). 



Idotea roHtrata Benedict, Proc. Biol. Soc. Washinjajton, XII, 1898, pp. 53-54. 



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

 Mag. Nat. Hist. (7), IV, 1899, p. 270; American Nat- 

 uralist, XXXIV, 1900, p. 228. 



Locality. — San Pedro, California. 



Body ol)l()ng-ovate, about two and a half times 

 longer than wide, 5 mm. : 12 mm. 



Head wider than long, 2i mm. : 8 mm., with the 

 anterior margin produced in the middle in a shortros- 

 trum, rounded at the apex. The antero-lateral an- 

 gles are prominent, rounded, and extend anteriorly 

 as far as the rostrum. The eyes are small, rounded, 

 and composite; they are situated at the sides of the fig. 437.-coLiDOTE.i 

 head. The first pair of antenna? have the basal arti- rostrata (Akter 



1 1 1 . 11 • .1 Benedict), x 3. 



cle somewhat enlarged; the three following articles 

 are short and nearlv subequal, the terminal one being a little longer. 

 The first pair of antennae extend to the end of the second article of 

 peduncle of the second pair of antennjie. The second antennie have 



«In the Proc. U. S. Nat. Mus., XXI, 1899, p. 843 (key) and p. 849, fig. 22, the 

 raaxilli|)ed is described and figured as composed of two articles. The maxilliped 

 appears two-jointed from the inner side, and the figure and the examination was 

 made from that side. In reexamining the material for the present paper, the mistake 

 was noticed and the correction is herein made. 



