496 



THE VOYAGE OF H.M.S. CHALLENGER. 



All the other plumes are pleurobranchial. The branchial arrangement is expressed 



in the following table : — 



Pleurobranchice, 

 Arthrobraricliue, . 

 Podobraneblae, 

 Mastigobranclriae, . 



1111 



k 1 m n 



In this genus the inferior extremity of each branchial plume is thrown forwards 

 (PI. LXXXVI. fig. 5), and not backwards as in Crcmgon (PL LXXXVI. fig. 2) and 

 Pontophilus (PI. LXXXVII. fig. 3). 



I only know of two species of this genus, and these are both from the south of New 

 Guinea. 



Pontocaris propensalata, n. sp. (PI. XC. figs. 2, 3 ; PI. LXXXV. fig. 5). 



Carapace narrower anteriorly than posteriorly ; furnished with five longitudinal 

 carinas, the three dorsal being multidenticulate and converging anteriorly ; the lateral 

 are also multidenticulate, the three anterior teeth being very large and culminating in 

 the frontal alas. Another longitudinal ridge, smooth but not keel-shaped, traverses the 

 infra-lateral wall of the carapace. Rostrum short and pointed, not extending beyond 

 the extremity of the ophthalmopoda. Fronto-lateral margin considerably produced 

 anteriorly. Dorsal surface of the pleon interruptedly carinated in the median line, and 

 corrugated laterally in oblique ridges. 



Ophthalmopoda small. 



First pair of antennae short. 



Second pair of antennas having a subcircular or discoid scaphocerite ; flagellum a 

 little longer than the carapace. 



