40 CRUSTACEA OF ALABAMA. 



Ascllus commuuis, Say, undoubtedly occurs in Alabama, perhaps also other species, 

 especially in caverns, would reward the student. 



Genus Mancasellus, Harger. 

 (= Asellopsis.) 



The genus differs from Aseilus in lacking the mandiblar palp and in the proportions 

 of the body. 



Mancasellus, s P- n - 



(Plate V, Fig. 8.) 



The species is known only from incomplete drawings and while closely allied to M. te- 

 nax, it seems to differ in proportions quite conspicuously. The lateral margins of the head 

 are emarginated as in M. tenax, the segments are more closely associated than in M. 

 tenax and the pleon is excavated in front on either side and is not truncate posteriorly 

 as represented in M. tenax, but rather acute. The caudal stylets are short, about as in 

 M. brachyurus, and the outer ramus is at least two-thirds as long as the inner. In M. 

 brachyurus, however, the sides of the head are said to be entire. While unwilling to ap- 

 ply a name to so imperfectly described a species, we can not doubt that it is new, having 

 been taken near Tuscaloosa, Ala. The small form figured in connection with the above 

 is apparently a larva of some member of this genus. (Plate V, Fig. 9.) 



ORDER AMPHIPODA. 



The waters of the Gulf abound in members of this order, which also is represented 

 in the rivers and pools. The "sand-hoppers" and "beach-fleas" may be sought 

 among drift wood and weeds along shore. Some species may be found wedged in. among 

 the foliage, while others hop about upon the shore, and still others swim freely. The 

 genus Allorchestes, represented by they4. dentatus so abundantly in the north, seems rare, 

 though specimens were seen in the northern part of the state, if memory can be trusted. 

 The genus Gammarus is well represented southward, while a much greater variety of 

 forms inhabits the brackish waters. The two species described beyond are the only 

 ones represented in our collections, though a species of Orchestia, like O. palustris, oc- 

 curs in myriads in Mobile bay. 



Gammarus mucronatus, Say- 



(Plate IV, Fig. 1.) 



Gammarus mucronatus. Say, Journ. Acad. Phila., I, part 4, p. 376. 

 Gammaracanthus mucronatus, Bate, Cat. Amph. Crust. Brit. Mus , p. 203. 

 (?) Gammarus semicarinatits, Bate, loc. cit. p. 204. 

 Gammarus mucronatus, Smith, Rep. U. S. Fish Com., 1871-1872, p. 559. 



