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Transactions. 



14. Gasterochisma melampus Ricliardson. 

 Plate VIII. 



by Uimtiiei in 1889 from a specimen driven ashore in Lyttelton Harbour 

 Gnnther enriched his account with a sketch of the entire fish, made by 

 Captain Hut43on an illustration of one of the scales, and of the skeleton as 

 mounted in the Canterbury Museum. ^^^wn, as 



nnt^L!^' ^^^"^^.^'^^^^tly ^f ^- suggested that the specimen thus named is 

 nothing more than the adult of Gasteroddsma melampus, described by 



Sir )U n^^ ^t''' J'^/' ^''""'^''^^y from a specimen obtained in Port 

 Nicholson (Welhngton Harbour). Gimther was quite aware of the likeness 

 of his Lepidothynnus to Gasterochisma, and if we accept the identity of the 

 two we must still regard the difierences produced by age as remarkable 

 thP f'l^ ""'' ' specimen was 8 in. in length, and we may especially notice 

 the ollowing points: The spmous portion of the dorsal fin is fully twice 

 the height of the second portion ; the pectoral is short, not half the length 

 ot the head ; while the ventrals are one-third the maximum length of the 

 specimen. Looking to the same features in Lepidothynnus, it is^'seen that 

 the dorsal lobe is twice^the height of the spines; the upper pectoral rays 

 are but .hree-fourths the length of the head, and a falcate shape is pro- 

 duced ; while, most remarkable of all, the ventrals, such a striking feature 

 ot the young, are quite insignificant, being but one-fourteenth the fen^th of 

 the fish as measured by Richardson. The disappearance of the full seSes of 

 scales on the cheeks and on the top of the head is not an uncommon feature, 

 but^the presence of the small corselet is not at all foreshadowed by Richard- 

 son s figure. J 



This author mentions that there is no vestige of a caudal keel The 

 whip AT', ^r ' ^"' r^ti^^^'/'idges, for they are not very prominent, 

 ri H T IS apparently reduced in extent, being traceable onk 



Zt7J}%"TT f'^f^''- J^ '^^ y«^"^g it IS figured as terminating in 

 advance of the hinder finlets, though described as passing through the ?ail 

 A comparison of Richardson's figure with the one now supplied shows that 

 the genei-al proportion and contour of the body is almost identical, the one 



Z^llll' % T'a" ^^""\ *^' P.'""^^' "^ *^^ ^^^^^^^ P«^'*i«'^' represented as 

 convex by Richardson, whereas m my specimen it is distinctly concave, as 

 tigured. It IS further noteworthy that the groove developed "in the young 

 for the reception o the ventrals, and extending from their insertion to the 

 anal fin, is retained for its entire length in the adult, notwithstanding the 

 fact that the ventrals are but one-fourth the distance indicated. Some 

 intermediate stages are clearly needed before the several peculiarities enume 

 rated can be satisfactorily traced. 



The illustration pubhshed by Giinther is stated to be simply a sketch 

 and must not, therefore, be taken too seriously ; but. as it formed the basis 

 tor portion of the description, its most discrepant features mav be pointed 

 out. It IS evident that the dorsal fin is incorrectly shown, and may be 

 due to a desire to conform to the skeleton, itself wrongly articulated. In this 

 tHe dorsal spmes are placed too far forward, making it appear that the fin 

 arises over the^opercle instead of some distance behind it ; the gap between 

 the spines and the lobe of the soft fin is therefore much too wide, both 



* Gunther, Chall. Rep., xxxi, 1889, p. 15, pi. vi 

 fRichardsor, Aim. Mag. Nat. Hist., vol. 15, 1845, p. 346 

 X Richardson, Voy. Ereb. and Terr., 1846, p. 60, pi xxxvli 



