ISOPODS OF NORTH AMERICA. 



419 



ill M. tena.r being armod with one broad low tubercle (in the sub- 

 species dilata the propodus is armed with three acute teeth), while in 

 J/, danielsi the propodus is armed with one large 

 tooth and one bluntly ending, ti'uncate process, 

 the dactylus being provided with two teeth at 

 the base, the dactylus in M. tenax being armed 

 with spines on the inner margin, of which the 

 distal ones are the larger, and at the end with 

 a large spine. 



This species differs from 2L lineatufi (Say) in 

 having antennae somewhat shorter, in the fact 

 that the propodus of the tirst pair of legs is 

 provided with a bluntly ending process between 

 the long tooth, situated about the middle on 

 the inferior margin, and the articulation of the 

 dactylus with the propodus, and in the longer 

 outer branch of the caudal stylets, it being half 

 as long as the inner branch, while in M. Uneatus 

 it is only one-third the length of the inner one. 



Named for Mr. L. E. Daniels, b\' whom the specimens were col 

 lected. 



Fifi. 471.— MANCASEIXrS 



DANIELSI. Lew of first 



PAIR. X 143. 



68. Genus ASELL.US Geoffroy. 



Mandibles with a palp. Last six pairs of legs with dactvlus uni- 

 unguiculate. E3'es present. 



Body broad, depressed. Head small, narrower and shorter than 

 first thoracic segment. 



Terminal segment of liody verv broad, not longer than broad. 



ANALYTIC.\L KEY TO THE SPECIE.S OK THE (JENl'K ASELLUS. 



Propodus of first pair of legs armed with two triangular procesnes, one or both 



processes sometimes replaced. by a strong spine. 

 h. Uropoda almost as long as the terminal segment of the ))ody. Fypimera present 

 on all the segments of the thorax, 

 c. Head with lateral margins not produced in a lol)e on eitlier side. Second 

 pair of antennae extend to the posterior margin of the fifth tlioracic seg- 

 ment. First pair of antenna' extend to the end of the peduncle of the 

 second antenn;e; fiagellum compo.sed of fourteen articles. 



Asellus communis Say 

 c^. Head with lateral margins produced in a lobe on either side. Second pair of 

 antennjc extend to the posterior margin of the seventh thoracic segment. 

 First pair of antenme extend to the middle of the fifth article of the pedun- 

 cle of the second pair of antenna:"; fiagellum composed of nine articles. 



Aselliis hi termed iioi Forbes 

 I/. Uropoda ahout half as long as the terminal segment of the body. Fpimera not 

 present on all the segments of the thorax. 



