ISOPODS OF NORTH AMERICA. 



FIG. 471. MANCASELLUS 

 DANIELSI. LEG OF FIRST 



PAIR. X 14|. 



iii J/i tenax being armed with one broad low tubercle (in the sub- 

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

 M. danielsi the propodus is armed with one large 

 tooth and one bluntly ending, truncate 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 M. lineatm (Say) in 

 having antennae somewhat shorter, in the fact 

 that the propodus of the first pair of legs is 

 provided wit'h 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. lineatus 

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



Named for Mr. L. E. Daniels, by whom the specimens were col- 

 lected. 



68. Genus ASELLUS Geoffrey. 



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

 unguiculate. Eyes present. 



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

 first thoracic segment. 



Terminal segment of body very broad, not longer than broad. 



ANALYTICAL KEY TO THE SPECIES OF THE GENUS ASELLUS. 



a. Propodus of first pair of legs armed with two triangular processes, one or both 



processes sometimes replaced by a strong spine. 

 b. Uropoda almost as long as the terminal segment of the body. Epimera present 



on all the segments of the thorax. 



c. Head with lateral margins not produced in a lobe on either side. Second 

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

 ment. First pair of antennae extend to the end of the peduncle of the 

 second antennae; flagellum composed of fourteen articles. 



Asellus communis Say 



</. Head with lateral margins produced in a lobe on either side. Second pair of 

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

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

 cle of the second pair of antennae; flagellum composed of nine articles. 



Asellus intermedim Forbes 



//. Uropoda about half as long as the terminal segment of the body. Epimera not 

 present on all the segments of the thorax. . 



