36 CRUSTACEA OF ALABAMA. 



curved, hairy process and a rounded prominence, above. Legs five pairs, normal. The 

 whole habitus is as in Moina, but the form of the shell, especially the head tend evident- 

 ly in the direction of Daphnia. Estuaries of Mobile Bay. 



Genus Simocephalus. 

 Simocephalus daphnoides, Hemck. 



S. daphnoides, Herrick, American Maturalist, 1883. 



Reference is here made to this interesting species because of its bearing on the sug- 

 gestions elsewhere made of the transitional character of the southern fauna. We have 

 in this species a complete link between Simocephalus and Daphnia, just as we see in 

 Moinodaphnia such a link with Moina. This species is as large as, and much of the 

 shape of Daphnia pulex (over one-tenth inch long,) head very small, depressed and 

 rounded, bearing the eye in the very front, lower margin straight, beak not produced, 

 pigment-fleck small, oval or irregular, fornices small and short, antennules small, with a 

 long sword-shaped spine near the base. Body oval or sub-quadrate, highest near the 

 middle (not posterior to it as in other species) shell with a blunt spine near the middle 

 and finely marked with anastamosing striae, not armed with a group of modified spinules 

 at the lower posterior angle. Post-abdomen narrow, very much as in Daphnia, armed 

 above with two slender processes for occlusion of the broad sac. 



Genus Scapholebris. 



This genus stands rather more isolated than either of the others and yet there are 

 not wanting evidence of near relationship with Ceriodaphnia and Simocephalus. In Al- 

 abama three species are known, one of which is not found abundantly north of the Ten- 

 nessee river. The others are widely distributed. The head is depressed, short, and the 

 continuation of the fornices runs toward the apex of the incurved beak, which common- 

 ly lies within the valves of the shell. The lower anterior angle has a prominence and 

 there is a basin-shaped area inclosing the base of the antennae, part ot which lies on the 

 shell and part on the head. This area is more strongly lined or reticulated than the rest 

 of the shell. The lower margin is straight and terminates, in most forms, in a long 

 scythe-shaped spine which is directed backward. The shell itself is usually indistinctly 

 reticulate or unmarked, and commonly is deep colored. The post-abdomen is very like 

 Ceriodaphnia or more as in Simocephalus ; the anal spines are few and the older speci- 

 mens have more than the young ; the place at which additional spines are to appear is 

 marked by prominences. The eye is of moderate size, the pigment fleck rather small 

 and the antennules short, and hidden by the beak. The antennae are of small size and 

 generally dark colored. The ephippium contains but one egg ; the males do not have 

 altered antennae or feet. The sexual periods fall in early summer and in autumn, ac- 



