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



fishes, because it has helped me to clear up the nature of certain young fishes, of which 

 I have known since the year 1860, without knowing to what genus they should be 

 referred. That these young fishes are pelagic is aniply proved by the three specimens 

 in the British Museum, all of which were caught in the open sea. 



1. The largest specimen is 26 mm. long, and was obtained in the tow-net on the 

 passage from Australia to the Cape of Good Hope, by J. B. Godfrey, Esq., who 

 however omitted to note the exact locality where it was captured. This is the specimen 

 which I mentioned in the year 1860 in the Catalogue of Fishes, vol. ii. p. 415, as 

 possibly representing the young stage of Mene maculata. 



2. A small specimen, 18 mm. long, was obtained by the Challenger Expedition in 

 July 1874, on the passage from Sydney to Wellington. 



3. Finally, for the third specimen, which is only 15 mm. long, we are indebted to 

 Mr. Wykeman Perry, who collected so many valuable specimens, whilst serving on 

 board H.M.S. " Pearl," under the late Commodore Goodenough. This specimen was 

 obtained in lat. 34° S., long. 12° E., in August 1873, that is, in the neighbourhood of 

 the Cape of Good Hope. 



The general form of these fishes may be best seen from the accompanying figui-e. 

 They are characterised by their extremely compressed body, the chest and the abdomen 

 forming a prominent sharp edge. The body is covered by a thick layer of silvery pigment, 

 the largest specimen besides showing distinct cycloid scales ; the lateral line runs parallel 

 to the profile of the back, which is much less curved than the lower outline of the body. 

 The back is occupied by a long dorsal fin, the anterior portion of which is spinous. The 

 anal fin is also long, preceded by three spines ; the ventral fins small, rudimentary, 

 inserted at a considerable distance behind the root of the pectoral and likewise at a 

 similar distance from the vent. 



The head is of moderate size without any armature ; eye of moderate size, the mouth 

 small and obliquely turned upwards. 



Although I have no doubt that these specimens are the young of Platystethus, I 

 consider it quite possible that the three specimens belong to as many distinct species on 

 account of the difference in the numbers of the fin rays. On -the other hand we have to 

 take into consideration, that owing to the very young age of these specimens, the posterior 

 tin rays may still be undeveloped. In the largest of these young specimens, which is 

 figured, the dorsal fin is composed of eighteen ^ spines and twenty-nine soft rays. The 

 anal is armed with three spines of which the third is very short, as is also the case in the 

 two other specimens ; of soft rays I count eleven. I found it impossible to ascertain the 

 number of dorsal spines in the two smaller specimens, without lacerating them in a 

 manner which would have impaired their utility in the future, but the soft rays were 



' A comparison with tlie specimens more recently acquireil has shown me that a numbiT of tlie rays in the dorsal 

 and anal fins, which I formerly in the largest specimen considered to be soft, are in reality spinous. 



