40 SQUALID.E. 



The family Squalidet is now composed of a greater mass of genera than 

 the Linneean genus Sqnalus formerly contained of species. They are cha- 

 racterised by the nature of the teeth, the presence, absence, or position 

 of the spiracles, of one or other of the dorsal or the anal fins, &c. &c.; and 

 appear as well established on these grounds as any of the older genera 

 in other tribes. 



Of these new groups, the little Shark exhibited in the accompanying 

 plate represents one of the best marked examples. The characters, however, 

 of this genus have but very recently been recognised ; and its claims to 

 such distinction are connected with a maze of singular confusion. Thus, 

 although possessing nothing of the elegance of a Callanthias, or of the 

 splendour of a Lampris^ this Acanthidium has become an interesting sub- 

 ject to the selachologist. 



The genus Spinax of Cuvier Avas established by its illustrious author 

 on the Squahis Jcaiithias, L. ; and in a note he proposes to add to it, with 

 some others, the Sq. Spinax, L. 



The genus Acanthias of Risso is exactly identical in type, extent, and 

 characters with Spinax, Cuv. 



The Sq. Spinax, L. proving, however, to differ generically from the 

 type and characters of Spinax, Cuv. (Acanthias, Risso), the Prince of 

 Musignano has more lately broken up the Cuvieran genus Spinax into 

 two, Acanthias and Spinax : the former differing only in extent, and not 

 in type or characters, from Spinax, Cuv. ; the latter founded on the Sq. 

 Spinax, L., and identical with Acanthidium, Lowe. 



The name of Spinax must, however, remain fixed to the type and 

 characters to which it was originally assigned by Cuvier, viz. the Sq. 

 Acanthias, L. and its true allies : for which Acanthias is, moreover, 

 an inconvenient designation, having been previously employed by Risso in 

 a different or wider sense, in which it is a mere synonym of Spinax, Cuv. 



For the Sq. Spinax, L. (Spinax niger, Buon.), and its allies, there 

 remains no alternative but to retain the name of Acanthidium, proposed 

 in the Proceedings of the Zoological Society for 1889. 



The group thus named and constituted, is well represented by the Shark* 

 here figured : and there is not, perhaps, amongst the Selachidee one which 

 possesses better claims to such distinction. It forms, in fact, a genus of 

 transition between the older groups of Spinax, Cuv., and Centrina, Cuv. ; 

 possessing, as I long ago remarked, -j- the elongated form of body of the 

 one, and teeth resembling rather — though it appears not to the extent 

 suggested by Cuvier''s account of them in Centrina — those of the latter 



* Judging from the descriptions, this Acant/iidium appears to be suffitiontly distinct specifically 

 from S(/. Spii/a.r, L. {Acanthidium >Spiuu,r, nob.) ; which differs chiefly in its paler colour, liairy skiu, 

 the dark-coloured inside of the mouth and breathing apertures, and the smaller pectoral fins. 



t Proceed. Zonl. Soc. 1833, i. 144. 



