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



Urolophus, M. and H. 



Urolophus kaianus. 



Urolophus kaianus, Giinth., Report on tlie Shore Fishes, Zool. Chall. Exp., part. vi. p. 37. 



Habitat.— OS the Ki Lslauds, Station 192, September 26, 1874; lat. 5° 49' 15" S., 

 long. 132° 14' 15" E.; depth, 140 fathoms; bottom, blue mud. 



HOLOCEPHALA. 



Chimcera, L. 

 Chimcera monstrosa, L. 



During the cruise of the " Knight Errant " a young male was obtained at the depth 

 of 555 fathoms (Station 4). The length of its trunk is 5 inches. The specimens caught 

 by the " Triton " are still younger ; two, a male and a female, having the trunk 2\ and 3 

 inches long, came from a depth of 516 fathoms (Station 10). Finally, a male, which 

 does not appear to have been long hatched, has the trunk only 1^ inches long ; it came 

 '^ from 565 fathoms (Station 11). 



These specimens are of considerable interest, as they show the gradual development 

 of certain organs. 



The youngest example has the caudal filament least developed, the length of the tail 

 measured from the vent, being little more than 3 inches, or twice the length of the trunk. 

 The tail is comparatively much longer in specimens of the next size, but as its extremity 

 is broken off in both, the exact proportion cannot be ascertained. In the largest of these 

 young specimens, with the trunk 4^ inches long, the tail measures not less than 

 17 inches. Of the fins only the first dorsal with its spine is developed. Of the anal 

 only a portion has appeared as a low ridge, but there is no trace of the second dorsal or 

 of the caudal. 



The development of the prehensile organ on the upper part of the snout, which is 

 peculiar to the male sex in Chimoira, keeps pace with that of the claspers. This 

 organ is visible in our youngest specimen, which evidently was hatched only a few 

 days, as a narrow cartilage of whitish colour entirely covered by the skin, but visible 

 through it. It has not made as great progress in the largest of the young specimens, 

 and therefore does not seem to become detached from the head before the individual 

 attains to sexual maturity. 



