NO. 1294. A XE W FRESH- WA TER ISOPOD—RICHA RDSON. 507 



of the fifth joint of the peduncle of the antennte, while in M. tevax it 

 is equal to the length of the fourth joint of that organ (the fourth 

 joint of the peduncle of the antennae in both species being shorter than 

 the fifth joint); in the greater breadth of the entir(» body in propor- 

 tion to its length, J/, tenax being narrower in widtii as compared to 

 its length; and in the difference in the legs of the first pair, the 

 l)ropodus in M. tenax being armed with one broad low tuljercle (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 l)luntly ending, truncate process, the dactylus being provided with 

 two teeth at the base, the dactylus in If. 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 J/! llucatus (Say) in having antenna^ some- 

 w hat shorter, in the fact that the propodus of the first pair of legs is 

 l)rovided with a ])luntly ending process l>etween the long tooth, situ- 

 ated al)out the middle on the inferior margin, and the articulation 

 of the dactylus with the propodus; and in the longer outer ])ranch of 

 tiie caudal stylets, it being half as long as the inner })ranch, while in 

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



Named for Mr. L. E. Daniels, l)y whom the specimens were col- 

 lected. 



