DAPHNIOIDEA. 



1269 



Head nearly separate, below long rostrate and acute. Posterior an- 

 tennae large, two-branched, the two branches two-jointed. Abdo- 

 men not inflexed, ending in two long corneous stylets and exte- 

 riorly not spinulous. 



This genus includes two marine species, very similar in character, 

 one obtained by the author at Rio Janeiro, and the other in the East 

 Indies. The shell is very large, having great vertical breadth, and 

 is open widely below ; the lower margin is sinuous and elegantly denti- 

 culate, and terminates behind either side in an acute point. The 

 posterior margin is also sinuous, and over the middle of the back, 

 as seen from above, is arcuately excavate ; the lower part of this 

 margin is denticulate. The head is but imperfectly separated by 

 a suture from the part behind; it has a long vertical front, and ends 

 below in an acute point or beak. The anterior antennae are very 

 small, and are situated towards the extremity of the beak on its inner 

 or posterior side. The posterior antennas are quite large. The 

 branches are nearly equal in length, and the second joint is very 

 short, the first being long. The eye is small. The thoracic legs are 

 narrow and of peculiar form (fig. 3, e, PL 89), unlike the other Daph- 

 nioidea described. There are two branches : one, the longer, nearly 

 terete, three-jointed, furnished on the lower side, like the base of the 

 organ, with a fringe of longish hairs ; the other, having an orbicular 

 extremity, which is set around with five to seven long setae, each 

 having an articulation not far from its base. 



The abdomen is two-jointed ; the first of the segments is about as 

 broad as long, and has at the dorsal apex a pair of small appendages, 

 each furnished with a long seta. The rest of the abdomen, exclusive 

 of the terminal stylets, is oblong, subterete, gradually diminishing in 

 breadth, and without spinules below. 



The egg cavity is rather large, the back of the animal being consi- 

 derably convex ; the largest number of embryos observed was six. 



Penilia avirostris. 



Testa postice ad medium profundi excavata. Setce appendicum abdo- 

 minis dorsalium stylis caudalibus multo breviores, basin stylorum fennd 

 attingentes. 



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