22 CRUSTACEA OF ALABAMA. 



0.5 mm. long. The integument is very dense and vesicular. The maxillipeds with their 

 powerful chelae are similar to those of Harpacticus. 



Amyone intermedia, s P- *■ 



(Plate I, Figs. 10, 11.) 



Our American species though so imperfectly known can hardly be indentified with 

 either of the known species. It most nearly approaches A. sphaerica, but differs in many 

 particulars. Head segment greatly produced, terminating in a sculptured margin like 

 the cephalic shield of Gammarus, etc.; three following segments nearly equal, the next 

 enlarged, the following smaller and succeeded by a series of" coalesced abdominal seg- 

 ments greatly produced below and serrately toothed, remaining abdominal segments small 

 and the stylets obscure. The antenna? appear to be 6- or 7-jointed ; antennules as in A. 

 sphaerica 3-jointed with a minute palp on the base ; outer maxilliped with a triangular 

 terminal segment more nearly as in A. longimana than sphaerica ; first feet long, the 

 rami short, 1 -jointed, remaining three pairs long and with both rami 3-jointed, fifth foot 

 in adult females very large, foliacious, 2-jointed. 



Gulf of Mexico. 



Genus Canthocamptus. 



The following species described in my Final Report are all the truly fresh-water 

 forms encountered in the Gulf states : 



Canthocamptus tenuicaudatus , Herrick. (By misprint C. tenuicaudis in Final Report.) 



Canthocamptus minutus, Mueller. 



A small species found in the brackish waters of Mobile bay seems to owe its peculi- 

 arities to the influence of the minute and varying quantity of salt in the water. 



Canthocamptus mobilensis. S P- «■ 



(Plate VI, Fig. 6.) 



A very small species closely related to. the American variety of C. northumbricus. 

 Body slender but closely knit, sub-cylindrical ; abdomen long, narrow, terete and of 

 nearly equal width ; head beaked ; eye large ; antennae short, eight-jointed, the third, 

 fifth and seventh segments being very short, fourth segment large and thick, bearing a 

 very large sword-shaped flagellum longer than the remainder of the antenna ; palp of 

 antennules small, tri-spinose; first foot with very short three-jointed rami; fifth foot of female 

 with five sub-equal spines on the inner lobe of the basal joint and two long and three 

 shorter spines on the end of the quadrate second joint ; Ova sac very large, spherical, 

 eggs numerous, large ; lower margins of the abdominal segments spinulous ; caudal sty- 

 lets short, sub-quadrate in outline, two setae, the inner being as long as the abdomen in 



