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



escent organs are present, some with a silvery centre, surrounded by a pigmentary ring, 

 others without the silvery centre. 



A specimen, 11^ mm. long, is semitransparent, whitish, without scales; of the phos- 

 phorescent organs only the one on the side of the head, covered by the prseopercular 

 limb, is visible as a black round pigment spot. 



Specimens, 9 mm. long, are without any trace of phosphorescent organs ; but the fins 

 and fin-rays are perfectly differentiated. 



This sj^ecies seems to lack the phosphorescent organs on the back of the caudal 

 peduncle. 



Diplophos. 



Diploplws, Giinth., Journ. Mus. Godeffroy, ii. 1873, p. lOL 



Body much elongated, band-shaped (covered with large thin deciduous scales ?). A 

 double series of phosphorescent organs runs along the lower side of the body and tail. 

 Head compressed, with pointed snout and projecting lower jaw. Mouth very wide but 

 slightly oblique ; jaws armed with small pointed teeth rather unequal in size ; eye of 

 moderate size ; paired fins well developed ; dorsal fin in advance of the anal, behind the 

 ventral ; adipose fin none ; anal very long. 



Di2)lophos tsenia (PL IV. fig. C). 



Dijplophos txnia, Gunth., loc. cif., p. 104. 



D. 8. A. ca. 43. V. 8. 



The length of the head is one-sixth of the total length, tlie greatest depth of the body 

 only one-sixteenth. Snout more than twice as long as the eye, pointed, with the lower 

 jaw longest. The maxillary reaches backwards far behind the eye. Dorsal fin short, its 

 first ray somewhat nearer to the end of the snout than to the root of the caudal ; anal fin 

 commencing below the last dorsal ray, and ending at a short distance from the caudal. 

 Paired fins short ; pectoral inserted near to the lower profile ; ventrals reaching nearly to 

 the origin of the dorsal. The phosphorescent organs are rounded black bodies, without 

 silvery centre ; they are very numerous and arranged in two parallel series along each 

 side of the lower profile. Those of the upper series are smaller than those of the lower, 

 are quite round and do not extend so far towards the head and the caudal, as the lower. 

 The lower are larger and transversely oblong. A pair of still larger luminous organs 

 occupies a position in front of the base of the lower caudal rays. Brownish.* 



The largest of three specimens is only 1-|^ inches long ; they were obtained at night 

 by the tow-net in lat. 30° S., long. 24° W.; and in lat. 22° N., long. 30° W. 



1 After fifteen years' immersion in spirit the colour of these specimens is faded into dull white. 



