34 CRUSTACEA OF ALABAMA. 



those of Latona in reversing the usual relation of the rami, as are also the elongate 

 antennules in the female. 



Pseudosida tridenta, Herrkk. 



(Plate III, Fig. 2-5.) 



P. bidentata, Herrick, Final Report. (Bv oversight the number of caudal teeth was misstated and the 

 name made to correspond.) 



Head very short, acute below, the beak bearing in the female a pair of rather large 

 antennules which are armed with a pectinate process three times the. length of the an- 

 tennule, and a cluster of about five sensory setae. The antennae are as long as in Sida 

 and well armed. The basal joint of the two-jointed branch bears seven setae, the sec- 

 ond ten setae of which two are apical ; three-jointed ramus with very short basal seg- 

 ment, second four times as long as wide and armed at the end with two setae and a spine, 

 third segment very small, with three setae and a minute spine. The maxilla is two-joint- 

 ed the terminal joint bearing nine jointed spines or short setae. The first foot of the 

 adult female is biramose, the outer ramus being large, its terminal joint bearing seven 

 pectinate processes, the preceeding segment has two processes on tbe outside, while the 

 short basal joint has a very large process, the outside of the base of the limb, with three 

 similar processes, inner ramus with five setae on the third and four each upon the second 

 third, inner margin of base of limb produced to form a multisetose branchial fin. Post- 

 abdomen rather small, its terminal claws short and armed with three basal spines and a 

 series of spinules along the inside, post-abdomen also ornamented with about twelve 

 clusters of teeth along the posterior margin and about the base of the claws. The egg- 

 stalk is long and about three out of every four eggs produced parthenogetically serves 

 as nourishment for the fourth, the ephippial females (i. e. the late females which produce 

 eggs coated to resist cold or drouth) are smaller than the ordinary examples and pro- 

 duce two very large ova. 



Family Daphnid.e. 



This family may be recognized by the presence of but five pairs of feet, the last 

 pair being smaller than and distant from the others ; antennules small, antennae cylindri- 

 cal with a three- and two-jointed ramus, the former with five, the latter with four setae, 

 intestine simple. 



The genera Daphnia, Simocephalus, Scapholeberis, Ceriodaphnia and Moina are all 

 represented and a new genus which fills very fully the gap between Moina, the least dif- 



