56 Description of Genera and Species. 



short rostrum which is expanded towards its base and hollowed out to form part of the 

 eye orbit. There is a distinct gastric prominence passing inwards from the base of 

 the rostrum, which is surmounted for a short distance by the crestal ridge of the 

 rostrum. Two deep almost semicircular depressions pass in from the lateral line on 

 each side, but do not meet in the mid-line. They may be the beginning of a cervical 

 fold or they may represent the collapsed bodies of the mandibles. Near the posterior 

 margin a transverse line crosses the carapace, which seems to indicate the presence of a 

 distinct segment showing through, owing to compression. 



The posterior angles of the carapace are rounded off and the posterior margin is 

 slightly hollowed out. Behind the margin of the carapace six free trunk segments 

 succeed each other. These are all constructed alike, as far as can be seen from above. 

 They are all slightly tumid, with a central dorsal crest and a depression marking off the 

 pleural portions from the tergites. 



The tail consists of the usual six segments and the telson. The anterior segments 

 are distinctly wider than those of the trunk ; like them they are tumid and have a 

 median dorsal keel, but they are supplied with distinct epimera, which are pointed and 

 are directed backwards. The tail narrows at the fifth segment, and is much constricted 

 about the middle of the sixth segment, which is appreciably longer than any of the 

 other segments, and is crossed b}' a distinct sulcus at the constriction. The central 

 ridge is continued through these segments. The telson is subquadrate, with nearly 

 parallel or only gently converging sides. It is divided into two areas, a front tumid 

 shield-shaped area and a posterior flattened area. The posterior margin of this 

 flattened portion gives off a process in the mid-line, and the margin on each side of 

 its base appears as if thickened for the articulation of accessory swimmerets. 



The eye is large and stalked, and appears to have been partially covered by the. 

 expanded base of the rostrum. The antennules have a three-jointed peduncle 

 surmounted by two flagella, the external one being the thicker and longer, but how 

 much so is not evident, as the exterior branch is broken. The antenna has a broad 

 basal scale, caridean in structure. The flagellum is more massive than the external 

 flagellum of the anteniuiles, and was probably much longer. As it bends off at right 

 angles and skirts the anterior margin of the scale, it is presumed that the peduncle of 

 the flagellum is the same length as the scale. 



The appendages of the sixth tail segment only are exposed. They consist of the usual 

 basal joint, which is moderately long and gives off the two usual plates. The exterior 

 one with its strengthening keel was evidently traversed by the usual transverse suture, 

 and the end lobe has l)een broken awav; the internal liranch, therefore, is seen to extend 



