ISOPODS OF NORTH AMERICA. 



379 



expansion, so that they seem more dorsal in position. The first anten- 

 nae have the basal article not enlarged; the second is about equal in 

 length to the first; the third and fourth are subequal, and each is about 

 one and a half times longer than the third. The first pair of antennae 

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



of antennae. The basal article of the 

 second pair of antennae is almost in- 

 conspicuous from a dorsal view; 

 the second article is short; the third, 

 fourth, and fifth are progressively 

 longer, each being one and a half 

 times longer than the preceding arti- 

 cle. The flagel- 

 lum consists of ten 

 articles. When 

 retracted, the sec- 

 ond antennae ex- 

 tend to the poste- 

 rior margin of the 

 third thoracic seg- 

 ment. The maxil- 

 lipeds have a palp 

 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 2. 



FIG. 413. SYNIDOTEA 

 PALLIDA. MAXIL- 



LIPED. X 27j. 



SYNIDOTEA EROSA Benedict. 



Synidotea erosa BENEDICT, Proc. A cad. 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. Sannakh Island, Alaska. 



Depth. 483 fathoms. 



Body oblong-ovate, three times longer than wide, 7 mm. : 21 mm. 



