^270 CRUSTACEA. 



Shell posteriorly over middle of back deeply excavate. Setae of dorsal 

 abdominal appendages not as long as caudal stylets, barely reaching 

 to base of stylets. 



Plate 89, fig. 2 a, side view of animal, enlarged ; b, dorsal view. 

 Harbour of Rio Janeiro, December 24, 1838 ; abundant. 



Length, one-twentieth of an inch. 



In dorsal view, head obtuse, very low triangular, sides of body 

 arcuate, posterior angles of shell prolonged, acute, nearly as remote as 

 greatest breadth of animal; centre of posterior margin deeply rotund- 

 excavate. In side view, back very much inflated, and within this part 

 there were six immature young. The head is lengthened down- 

 ward, appears acute, and terminates in a short acute appendage 

 (rudimentary anterior antennae). 'The lower margin of the shell is 

 rounded anteriorly, then nearly straight but undulate, and both this 

 and the lower half of the posterior margin is set with minute teeth. 

 The antennse have a long subcylindrical base, and two smaller and 

 somewhat shorter branches ; the branches are subequal, consist of a 

 long slender joint and a very short apical, and bear a few setae at 

 apex, hardly as long as the branch. 



The abdomen extends beyond the carapax ; it has a subcylindrical 

 form, and terminates in two curved setae, longer than the abdomen. 

 From near the base of dorsal part of abdomen, there is a pair of 

 minute appendages, slender in form, bearing one or two slender setae; 

 the tips of the setae extend nearly to apex of abdomen, or not 

 beyond it. 



Penilia avirostris, Dana, Proc. Amer. Acad. Sci., ii. 47, 1849. 



Penilia ORIENTALIS. 



Testa jpostice ad medium parce excavata. Setoe appendicum abdominis 

 dorsalium Icmgissimai, apicem stylorum caudalium superantes. 



Shell shallow excavate posteriorly over middle of back. Setae of 

 dorsal abdominal appendages very long, reaching even beyond apex 

 of caudal stylets. 



