﻿OSTEOLEPIDiE. 389 



It seems probable that the following insufficiently characterized 

 genera and species are founded upon scales of Osteolepidoo : — 



Plintholepis retrorsa, H. Romanowsky, Bull. Soc. Imp. Nat. 



Moscou, vol. xxxvii. (1864), pt. ii. p. 169, pi. iv. fig. 37. 



— Carboniferous Limestone ; Government of Toula. 

 Sporolepis pyriformis and S. erassa, H. Romanowsky, ibid. 



p. 169, pi. iv. figs. 38 a, b.— Ibid. [? Fulcral scales.] 



Genus GLYPTOPOMUS, Agassiz. 



[Poiss. Foss. Y. G. R. 1844, p. 57.] 



Syn. Platygnathus, L. Agassiz, ibid. p. 77 (in part). 



Glyptolcemus, T. H. Huxley, in Anderson's Dura Den, 1859, p. 63. 



Head-bones in advance of the parietals not fused into a continuous 

 shield ; frontals separate, with a median foramen ; head-bones, 

 operculum, and jugular plates ornamented with irregular reticula- 

 ting rugas or fused series of tubercles, apparently coated with a very 

 thin layer of ganoine ; no anterior median jugular plate. Anterior 

 dorsal fin opposed to the pelvic pair and the posterior to the anal ; 

 tail diphycercal, with a rhomboidal caudal fin. Scales with broad 

 overlapped border, externally ornamented with tubercles and reti- 

 culating rugae of ganoine. 



The characteristic external ornamentation of this genus seems to 

 be due to the special development of the rugosities so characteristic 

 of Megaliclithys when the superficial ganoine is removed. Though 

 ganoine is sometimes stated to be absent upon the dermal skeleton 

 of Glyptopomus, the present writer is of opinion that an extremely 

 thin layer occurs. 



Glyptopomus minus, Agassiz. 



1844-45. Platygnathus minor, L. Agassiz, Poiss. Foss. vol. ii. pt. ii. 

 p. 162 (name only), and Poiss. Foss. V. G. R., lettering of 

 pi. xxvi. 



1844. Glyptopomus minor, L. Agassiz, Poiss. Foss. V. G. R. p. 57. 



1859. Glyptopomus minor, J. Anderson, Dura Den, p. 55, pi. ii. 



1866. Glyptopomus minor, T. H. Huxley, Figs. & Descrips. Brit. Or- 

 ganic Remains (Mem. Geol. Surv.), dec. xii. p. 4, pi. i. figs. 1, 3, 4. 



Type. Imperfect head and trunk, dorsal aspect ; British Museum. 



The type species, attaining a length of about 0*4. Head with 

 opercular apparatus contained about five times in the total length : 

 jaws much elongated ; principal jugular plates rapidly tapering and 



