﻿OSTEOLF.PIDjE. 



375 



The attenuated caudal lobe is distinctly exhibited, and is 

 fringed above by a series of short fin-rays. 



Purchased, 1879. 



33140. Trunk with pelvic, dorsal, and anal fins, and the base of 

 the caudal; Thurso. The specimen is shown, of the 

 natural size, in PI. XIII. fig. 3, and the fins indicated by 

 the lettering. Adjoining each dorsal fin is a very large, 

 antero-posteriorly elongated ridge-scalc. 



Purchased, 1857. 



42440. Imperfect head and trunk, wanting the extremity of the 

 tail and the anal fin ; South Head, Wick. Large conical 

 teeth, simple in section, are shown in the jaws ; and the 

 lobation of the paired fins is distinct. Peach Coll. 



Genus DIPLOPTERUS, Agassiz 1 . 



[Poiss. Foss. vol. ii. pt. i. 1835, p. 113.] 



Cranial roof-bones in advance of the parietals fused into a con- 

 tinuous shield, with a median frontal foramen ; an anterior azygous 

 jugular plate present. Teeth rounded in transverse section. Dorsal 

 fins opposed to the pelvic pair and the anal respectively. Tail 

 almost diphycercal ; caudal fin unsymmetrically rhomboidal, the 

 upper lobe somewhat smaller than the lower. Scales smooth and 

 punctate. 



Diplopterus agassizi, Traill. 



1841. Diplopterus agassis, T. S. Traill, Trans. Roy. Soc. Edinb. vol. xv. 



p. 89. 

 1844. Diplopterus macrocephalus, L. Agassiz, Poiss. Foss. V. Gr. R. 



p. 54, pis. xvi., xvii. [British Museum and Forres Museum.] 

 1844. Diplopterus affinis, L. Agassiz, ibid. pp. 55, 138, pi. xxxi. a. 



fig. 27. 

 1844. Diplopterus borealis, L. Agassiz, ibid. p. 55, pi. xviii. fig. 1 (? fig. 2). 



[Olim T. S. Traill Collection.] 

 1848. Diplopterus gracilis, F. M'Coy, Ann. Mag. Nat. Hist. [2] vol. ii. 



p. 305. [Woodwardian Museum, Cambridge.] 



1 This generic name is preoccupied (Latreille, 1817, and Boie, 1826), and 

 M'Coy accordingly proposed the slightly modified, though essentially identical, 

 form Diplopterax. As, however, the fish in question has been universally 

 quoted for fifty years under the name of Diplopterus, we are unwilling to 

 suggest a change which would necessitate future ichthyologists adopting a dual 

 nomenclature. 



