OSTEOLEPIDJE. 
389 
It seems probable that the following insufficiently characterized 
genera and species are founded upon scales of Osteolepidae:— 
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. crassa , H. Romanowsky, ibid. 
p. 169, pi. iv. figs. 38 a, b. —Ibid. [? Fulcra! scales.] 
Genus GLYPTOPOMUS, Agassiz. 
[Poiss. Foss. Y. G. R. 1844, p. 57.] 
Syn. Platygnathus, L. Agassiz, ibid. p. 77 (in part). 
Glyptolcemus, T. II. 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 rugae or fused series of -.tubercles, apparently coated with a very 
thin layer^€>f ganoine; no anterior median jugular plate. Anterior 
dorsal fin opposed to the pelvic pair and the posterior to the anal; 
tail diphycereal, 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. ^ . 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 04. Head with 
opercular apparatus contained about five times in the total length: 
jaws much elongated ; principal jugular plates rapidly tapering and 
