158 THE VOYAGE OF H.M.S. CHALLENGER. 



do not differ materially from those of Cypridina ; eacli is provided with a large oval 

 branchial plate, and the spines of the various segments have strongly-toothed margins ; 

 the third maxilla (fig. 9) is composed of three or four short digitiform segments, which 

 are densely clothed with short, stout setae, and attached to these is a large snbtriangular 

 lamina, which bears along its outer margin several rows of plumose setse ; these are 

 separated by a short interval from another series of about six branchial filaments which 

 are attached to an apical process of the plate. The postabdominal laminse (fig. 11) are 

 beset with numerous strong curved marginal claws, which appear to be arranged in 

 several series of two or three claws each, those of each set being graduated as to size and 

 strength. Some of these claws are drawn in situ in figure 11, while the scars showing 

 the points of attachment of the others show a gradation of size like that here described. 

 The copulative organs of the male (fig. 10) consist of a right and left limb, one of which 

 is hamate, the other obtuse, and beset at the apex with numerous spine-like setae ; both 

 are attached to a large basal segment, from which springs also a stout process bearing on 

 its expanded apex a series of nine curved setae arranged in a somewhat fan-like manner 

 and regularly graduated in length from one end of the series to the other. Some other 

 points of structure in the organs I have not been able clearly to make out. Oviferous 

 foot, almost exactly like that of Cypridina. 



1. Grossophorus imperator, n. sp. (PI. XXXVIII. figs. 1-11). 



Shell dense, porcellaneous and polished ; seen from the side, broadly and regularly 

 oval ; height equal to three-fourths of the length, notch of moderate size, and exjDanded 

 laterally so as to produce two obliquely-placed depressed areas on the anterior face of the 

 shell ; beak curved and sharp ; posterior extremity broadly rounded, dorsal and ventral 

 margins equally convex ; seen from above, the shell is oblong ovate, widest in the middle, 

 subacuminate in front, and rounded behind, width equal to more than half the length ; 

 end view ovate. Length, ^d of an inch (8*4 mm.). 



Of this noble species, certainly the largest of the known Cypridinidae, one specimen 

 was dredged in a depth of 1100 fathoms, in lat. 40° 28' S., long. 177° 43' E., the 

 bottom temperature being 2"0 C. 



The possibility should be borne in mind, however, of the creature having been 

 captured in the upward passage of the dredge through the water. The characters of 

 the genus are very like those of Brady cinetios, Sars, but the secondary branch of the 

 posterior antennae in the latter genus does not end in a claw, while the structure of 

 the third pair of maxillae, and the general style of setose and spinous armature seem 

 to be so abnormal as to require the establishment of a new genus for their due ex- 

 pression. 



[PL XXXVIII. figs. 1-11. 1 Carapace of the male seen from right side, 2 from above, 

 3 from front (magnified 6 diameters), 4 anterior antenna, 5 posterior antenna with (o) 



