498 PROCEEDINGS OF THE ACADEMY OF 



under the name of A cant Mas, by Muller and Henle, and has the same limits that 

 appear to have been intended for it by the Prince of Canino. It embraces only 

 ibose species which possess all the characteristics assigned to the genus Acan- 

 iHas by Muller and Henle, and which in addition agree in the relative situation 

 of the ventral fins, and the form of the pectoral and caudal fins. The Squalus 

 uyato of Rafinesque is thus excluded. This species differs from Squalus acanthias 

 and the allied species, by the distinct terminal lobe with which the caudal fin is 

 provided, the obtuseness of the external angle of the pectoral, and the acute pro- 

 longation of the internal one, as well as the posterior insertion of the ventrals, 

 those fins being but little in advance of the second dorsal. The transverse 

 grooves or pits at the base oftbe caudal fin are also obsolete. It cannot be doubted, 

 that this combination of characters is indicative of generic distinction from the 

 Squali. The Squalus uyato should then be regarded as the type of a peculiar 

 genus, and in allusion to one of the characters which distinguishes it from 

 Squalus, it may be named EnloxycMrus uyatus. This species has been referred 

 with doubt to the genus Spinax as distinguished from AcantMas, by Bonaparte, 

 but it evidently does not belong to that group, and is more nearly allied to the 

 latter, in which it has been placed by Muller and Henle. 



The name of Squalus has been retained for this genus instead of AcantMas, 

 because it was first restricted to the group. 



The genus Squahis of Artedi and Linnaeus was equivalent to the order of 

 Squali ; its species were distributed by Rafinesque among a number of smaller 

 groups or genera, and by him the name was first retained for those species 

 which are deprived of an anal fin and have a blunt back. As Rafinesque was 

 perfectly justified in this limitation, the name of Squalus must be preserved for 

 a portion of that group, and having been first in this limited sense applied to 

 the species with spinous dorsals, must be so retained. Rafinesque's genus 

 Squalus, however, was co-extensive with the fourth section of Muller and 

 Henle, after the exclusion of the genus Cenlrina and the family of Squatinae; it 

 embraced all the species with an obtusely trihedral or subcylindrical body and 

 without an anal fin. At the same time, under a misapprehension, supposing 

 that some species were destitute of spiracles, he referred them to another genus 

 called Dalatias, not perceiving the identity of those species with some that be 

 bad already placed in the geuus Squalus. 



In 1816, Blainville proposed the generic name AcanthorMnus for a group 

 which is co-equal with Squalus and Oxynotus of Rafinesque, referring to it all 

 the species of Squali without an anal fin, and with the first dorsal fin on the 

 back, in contradistinction to EcMnorMnus in which both dorsals are on the tail.* 

 Squalus was not retained as the name of a subgenus. 



Again, in the following year, Cuvier distributed the same representatives of 

 the suborder Squali among three genera; Spinax, distinguished by the pre- 

 sence of dorsal spines, and the advanced insertion of the ventral fins ; Centrina, 

 with spinous dorsals the second of which and the ventrals were opposed Jo 

 each other, and Scymnus, the dorsals of which were unarmed. He likewise 

 omitted to retain the Artedian name for any minor group or subgenus of 

 Squali. 



The name of Spinax was retained unaltered for the group so called until the 

 Prince of Canino, in 1838, restricted it to the Squahis spinax of Linnasus, and 

 referred the S. acantMas to a new genus which was named AcantMas. TheBe 

 names were retained for those groups till 1862. 



In the "Analytical Synopsis of the order of Squali," the history of the nomen- 

 clature of the genera of that order was briefly discussed, and it was urged 



*6. Acanthorhinus, Car. Dent. var. ; IrjRp. magnis ; P. S. 2, 1, in dorso; 2, m3gna; P. A. nulla; 

 C. lata, bifurcata. lobo sup. brevi. Cute asperrima. 



Spec. Acanthias; Kerdinandinus ; Assierii; Spinax: Morwegianug; Amerieauue aut Nicensic ; 

 Murocephalua; Centrina; Squamosus; (iranulosus; Opeditinus ; Biochianue. (Journal do Phy- 

 sique, &., lxxxiii. p. 263 ) 



[Oct. 



