some Entomostraca. 25 



segment of the branches bears one long hair, and the apical one of 

 each five, the small slender apical spine of the first pair of legs 

 being developed into a strong hair, plumose on the inner and ser- 

 rated on the outer margin. 



Fifth pair of legs are "05 in length ; both legs are five-jointed. 

 The smaller leg ends in a sort of round knot, and bears a large 

 spine at the apex of the third segment, and a small inner branch 

 at the apex of the second segment. The larger leg consists of two 

 branches ; the inner one small, and appears to have three rudi- 

 mentary joints, the larger branch has the two first joints large, the 

 apical longer than the preceding segment, bearing a large spine 

 near the middle, slender, and terminating in a fine point. 



Abdomen is '036 in length, four-jointed ; the first segment 

 rather short, the three following nearly equal, the caudal lamellae 

 very short and small, bearing four hairs, of which the second is the 

 longest. 



This species was collected in 27° 30' N. L., 25° W. L. 



I have found no females which I could refer to this species, but 

 this is not to be wondered at, as I only had three or four spe- 

 cimens. 



PI. IX. figs. 3, 4, 5. 



Undina Helence, n. s. 

 Maris. — Cephalothorax 5-articulatus postice obtusus, articulis 

 tribus posticis subaequis. Frons triangulata. Antennae an- 

 ticae corpore parce breviores ; seta articuli secundi (tertii?) 

 longd, leviter flexa, seta ai)icali postica longd, antica penul- 

 tima sublonga, postica brevi, posticd ante-penultimdarticulum 

 vix superante, aliis brevibus. Abdomen 4-articuIatum, arti- 

 culis subeequis ; styli caudales parvi. 

 The second pair of antennae have the accessory branch nearly 

 twice as long as the organ itself. The four small intermediate 

 joints are hardly distinguishable, but are indicated by the usual 

 five long hairs. At the apex of the organ itself the one tuft con- 

 sists of six subequal hairs, the other of four long hairs and three 

 smaller ones. 



The third pair of maxillipeds are formed as usual ; but there is 

 this peculiarity, that the fourth segment, counting from the base, is 

 larger than the third, as in the longipes. The two basal segments 

 are like those of Calanus and not like those of Euchcela. 

 Length -028. 



The first pair of legs have the outer ramus three-jointed ; and 

 the inner one, I believe, two-jointed. 

 Length -025. 



