REPORT ON THE CRUSTACEA MACRURA. 275 



distinction, and brings this genus in its branchial arrangement near to Spongicola and 

 Stenopus, which it also approaches in the absence of the small basisal branch of the 

 second pair of gnathopoda, which is rudimentary in these genera. 



The general resemblance of some species to each other is very close, while others arc 

 easily distinguishable. 



This genus very much resembles Solenocera, Lucas, from which in external struc- 

 ture it differs in having the flagella of the first pair of antennas cylindrical, instead 

 of one being grooved to receive the other. 



I have not had an opportunity of examining the branchial arrangement of any 

 species of Solenocera, and therefore cannot compare it with that genus. 



It may from the description be mistaken for Penseopsis, A. Milne-Edwards, from which 

 it can readily be distinguished by the form of the carapace, by the presence of post- 

 orbital and postantennal teeth on it, and by the length of the peduncle of the first pair 

 of antennas. 



It differs from the typical Penzeus in having two arthrobranchise attached to the 

 membranous articulation of the penultimate pair of pereiopoda, and in all the mastigo- 

 branchise being remarkable for a knee-like bend, by which the basal portion lies at right 

 angles to the terminal half, which is placed between and separates the branchial plumes, 

 and is liable to vary in form in different species. 



Geographical Distribution. — Species of this genus have been found in the Sea of 

 Banda, off the Kermadec Islands, among the Celebes Islands, off the Ki Islands, and in 

 the Arafura Sea. 



Penseus siphonoceros, Philippi and Heller, is undoubtedly synonymous with Penseus 

 membranaceus of Milne-Edwards, and belongs to this genus, but not with Peneeus 

 membranaceus of Risso, from which it differs in the flagella of the first pair of antennae 

 not being distally truncated, nor in having the upper ramus longitudinally enclosed within 

 a groove in the lower. 



Pemeus crassicornis, Milne-Edwards, also belongs to this genus, and is recorded 

 by him as inhabiting the coasts of India. Sir Walter Elbot, S.I., F.E.S., procured 

 numerous specimens at Waltair on the coast of Madras. 



Philonicus miilleri, n. sp. (PI. XXXIX.). 



Carapace dorsally furnished with a small carina that commences at the posterior 

 margin and continues anteriorly to the rostrum, which is armed on the upper margin 

 with eight teeth in the female and with nine or ten in the male ; the lower margin is 

 smooth, slightly curving upwards to the extremity, and fringed with a row of hairs. 

 The anterior margin of the carapace has an orbital and a first-antennal tooth, behind 

 which are a postantennal and a hepatic tooth. 



