Mr. J. Y. Johnson on a new Trichiuroid Fish. 285 



" Coelho " of Madeira (Thyrsites Prometheus, Gthr. ; Prometheus 

 utlanticus, Lowe). From that fish it may be distinguished by the 

 possession of a dagger-shaped spine in front of the anal fin*, by the 

 spines of the first dorsal fin being twenty-one in place of eighteen, 

 by the rays of the second dorsal fin being nineteen in place of twenty- 

 one, and by the rays of the anal fin being eighteen in place of six- 

 teen. It may be further noticed that in the present fish the ventral 

 spines are placed under the posterior angle of the base of the pec- 

 toral fin, instead of being inserted a little before that fin, and that 

 the lateral line does not descend rapidly under the anterior part of 

 the first dorsal fin, as in Prometheus atlanticus. With Nesiarchus 

 nasutus it cannot be confounded, since the latter has perfect ventral 

 fins and fleshy and cartilaginous prolongations of the jaws. 



The dimensions of the fish which has afforded materials for this 

 description are given in the following table : — 



inches. 



Total length of fish 10 



Height 1^ 



Thickness behind pectoral , -fa 



Head, length 2 fa 



Eye, diameter, nearly 2 



Teeth, length of largest £ 



First dorsal, distance from muzzle 2 



First dorsal, length 4^ 



First dorsal, height in front -fa 



Second dorsal, length ] fa 



Second dorsal, height -fa 



Pectoral, distance from tip of lower jaw 2-^ 



Pectoral, length Ifa 



Ventral spines, length | 



Ventral spines, distance from tip of lower jaw .... 2fa 



Spine in front of anal, length fa 



Anal, length 1^ 



Anal, height in front fa 



Caudal, length 1 1 



The family of Trichiurid<e is composed, according to Dr. Giinther's 

 Catalogue, of the genera Aphanopus, Lepidopus, Trichiurus, Epiti- 

 nula, Dicrotus, Thyrsites, and Gempylus. To these have to be added 

 the recently described genera Nesiarchus and Nealotus. With re- 

 spect to Dicrotus, Giinther, a genus founded on a small fish only 

 1\ inches in length, it appears to me that it ought to be abolished, 

 the fish having been most probably a young individual of some species 

 of Thyrsites or Gempylus — an opinion which has been entertained by 

 Dr. Giinther himself for some time. From Thyrsites Prometheus, 

 for example, it would seem to differ only by the absence of finlets 

 and the presence of minute teeth on the vomer. But finlets are not 



* Aphanopus carbo, Lowe, and Nesiarchus nasutus, a fish described by me in 

 the Society's ' Proceedings' for 1862, p. 173, pi. xxn., have a similar spine be- 

 tween the vent and the anal fin. 



