258 A HISTOEY OF EECENT CEUSTACEA 



and broad tridentate frontal plate, and leaves the last 

 seo-ment of the trunk dorsally uncovered. The scale of 

 the second antennae is broad and heart-shaped with a 

 fringed inner margin. The elongate telson terminates in 

 some strong spines and a little serrate plate. 



Geratolepis, G. O. Sars, 1883, has also only one species, 

 Ceratolejns hamata^ which much resembles the preceding, 

 but its hard and large carapace leaves no segment of the 

 trunk uncovered. The scale of the second antennae is 

 narrow and flexuous, forming a sort of hook on either 

 margin, with no fringe of hairs, and the telson is not 

 truncate at the apex but cleft into two diverging lappets, 

 ' somewhat resembling the tail of a swallow.' The single 

 specimen was scarcely half an inch long, and hence the 

 smallest of the known Lophogastridas, and, though its 

 organisation seems to mark it out as a deep-sea form 

 like the rest of the family, it was in fact taken at the 

 surface of the Pacific. 



Gnathojjhcmsia, v. Willemoes Suhm, 1879, has a 

 parchment-like integument, the carapace in front drawn 

 out into a long spear-shaped and denticulate rostrum, and 

 behind in general into a backward pointing spine. ' The 

 greater part of the carapace, as in the genus Nehalia, 

 would appear to form, so to speak, merely a loose mantle 

 arching the back and sides of the trunk, and within which 

 the body is freely movable.' This part is surmounted by 

 two longitudinal keels on each side. On the upper side 

 of the eye-stalk there is always a small prominence called 

 the ocular papilla. Of the first antennae the outer 

 flagelluai is very long and so compressed as to be almost 

 ribbon-shaped. The scale of the second antennae is 

 variable. The first maxillae hav^e on the outer side of the 

 basal part a two-jointed ' palp,' which, contrary to what 

 is the case in the other Podophthalma, is bent directly 

 backwards. Though looking like an epipod, this appears 

 to be part of the endopod. Both joints are armed with 

 setae or bristles, those on the second joint elongate, the 

 apparatus being no doubt destined to sweep the branchial 

 cavity, as is the case with the similar formation in the 



