REPORT ON THE CRUSTACEA MACRURA. 495 



membranous hair-like appendages, and the basal joint is fringed on the inner side with a 

 thick mat of ciliated hairs. 



The eco-s are ovate and larger than in Crangon, and the brephalos probably quits the 

 ovum in a more advanced condition, inasmuch as in the embryo I have been able to 

 detect the pleopoda in a budding state of development. 



Pontocaris, n. gen. 



Rostrum short, not longer than the ophthalmopoda. Fronto-lateral margin of 

 the carapace much dilated and anteriorly produced. Dorsal surface multicarinated. 

 General appearance as in Crangon, except that the scaphocerite is not longer 

 than the peduncle of the first pair of antennas. The second pair of gnathopoda 

 is long, reaching beyond the distal extremity of the first pair of antennae, and is 

 furnished with a short basecphysis but no mastigobranchia. 



The first pair of pereiopoda is robust, subchelate, and furnished with a short uni- 

 articulate ecphysis attached to the basis. The second pair is slender, nearly but not quite 

 as long in proportion to the first as in Crangon, and chelate. Third pair long, slender 

 and styhform, reaching beyond the extremity of the first pair. The two posterior pairs 

 are simple and robust. 



The pleopoda are broad and foliaceous, and the outer plate of the rhipidura has no 

 diaeresis. 



This genus differs very considerably in its external appearance from Crangon, most 

 conspicuously in the development of the antennal region and the frontal margin of the 

 carapace, which is dilated and produced in the form of small wings. But a careful 

 examination of the several parts shows that the two genera approximate to each other 

 in detail. All the appendages of the cephalon and pereion closely agree with those of 

 Crangon, and the differences distinguishing the two are of little value. The 

 ophthalmopoda are smaller in Pontocaris than in Crangon, and the first pair of antennae 

 has the outer flagellum larger at the base ; the scaphocerite of the second pair is short 

 and discoidal, whde in Crangon it is long and narrow ; and the mandibles and oral 

 appendages have no appreciable distinguishing character from those of Crangon. The 

 branchial appendages, however, exhibit differences of more importance. In Crangon 

 the first pair of gnathopoda carries a small and almost rudimentary mastigobranchial 

 plate, whereas in Pontocaris there is a small podobranchial plume attached to the 

 mastigobranchia. On the second pair of gnathopoda I cannot find the rudiment of 

 the mastigobranchial plate, and the arthrobranchiae are also wanting, but are repre- 

 sented by a pleurobranchial plume. 



