Hamilton. — Occurrence of Genus Trachipterus in New Zealand. 379 



in regard to the position and size of the spots, but in the relative proportions 

 of the body. The Purakanui specimen is deeper, the body being contained 

 5 times in the total length, while the depth of the Chatham Island specimen 

 is contained 5j times therein (excluding the caudal fin in both cases). 

 This may be accounted for by the fact that the smaller specimen is young, 

 while the Chatham Island fish is probably the adult form. In other respects 

 — -viz., shape of head and position of eye, nature of fin rays and spines, 

 position and shape of spots, texture of integument, and other characters 

 — the fishes are identical. 



The specimen from Port Chalmers has a fifth .spot not present in the 

 other examples. 



In discussing the variations in T. taenia, Emery writes, " The distribu- 

 tion of spots is not constant, and is therefore fallacious for specific purposes. 

 , . . In one example I have seen four spots in the dorsal series." 



The three specimens imder consideration illustrate successive stage- 

 growths of the same species, the Chatham Island .specimen the mature 

 form, the Portobello example being more developed than the juvenile 

 Purakanui fish. 



Professor Benham has drawn my attention to the similarity of Clarke's 

 drawing of T. arawatae to Emery's illu.'^tration of T. spinolae Cav. & Val. 

 The main difference lies in the fact thtit T. spinolae has 3 spots that are 

 not represented in T. arawatae. 



The outstanding features of this last-named species, the type of which 

 I have examined, are the rudimentary dorsal and ana] fins. The ventral 

 rays are extremely long, and, with other characters, indicate that the 

 specimen is young. 



McCoy's smaller figured specimen of T. taenia shows an apparently 

 rudimentary anal fin. The larger example, admitted to be the same species, 

 shows only traces of such a fin. Clarke made an error in separating the 

 rudimentary dorsal from the continuous dorsal, for the specimen shows 

 no signs of a break. 



Throughout th^ genus Trachipterus there are indications pointing to 

 the degeneration and disuse of the anal and ventral fins, and the idtra- 

 development of the dorsal appendages. Even the caudal fin is assuming 

 an almost ^'ertical position, and usurping the functions of a dorsal fin. It 

 is onh' in the juvenile forms that any signs of the existence of ventral and 

 anal appendages can be recognized. The cause for the degeneration of 

 these fins must remain obscure until we know more about the life-history 

 of these extraordinary fishes. 



In discussing his specimens of T. taenia, McCoy(5) observes that " the 

 young are deeper and shorter in proportion than the old, and consequently 

 specific differences founded on the greater number of times the length of 

 the head or the depth of the body are contained in the whole length are 

 not to be trusted for specific characters when the length of the specimens 

 is different." It may be noted that McCoy's young specimen of T. taenia 

 has no black .spots, as is also the case in T. arawatae. 



Emery (1) demonstrated that in T. taenia the fin rays commence to 

 grow when the young is about 6 mm. long, and continue to lengthen till 

 the fish is about four times that size, after which period a shortening of 

 the rays takes place. 



Jordan and Snyder(12) now think that T. ijimae is a young specimen 

 of T. ishikawae. On consulting the original descriptions and the two 

 figures, one would pronounce the specimens to be distinct, for no two fishes 



