188 REPORT—1874. 
M. stmpLex, Young. 
“ Pulp-cavity larger ; folds straight, the alternate long plice reaching only half- 
way from circumference to pulp.” 
Locality. Lanarkshire Coal-field. 
Reference. Thomson & Young, Brit. Assoc. Report, 1869, ii. p. 101. 
Megalocephalus, Barkas. 
To judge from the figure, this genus is based upon the posterior part of a skull of 
Loxomma. Mr. Barkas enumerates it among the true Reptilia. 
M. macromma, Barkas. 
Locality. Low-Main Coal-Shale, Northumberland. 
References, Barkas, Coal-measure Paleontology, p. 69 [1873 ].—Atlas of Carbo- 
niferous Fossils, t. ix. fig. 189 [1873]. 
Mesosaurus, Barkas. 
M. Taylori, Barkas, respecting which we have no information, is enumerated by 
Mr. Barkas among the Amphibia of the Northumberland Coal-field (Manual of 
Coal-measure Palzontology, p. 116). 
Molgophis, Cope. 
“ The characters of this genus are :—Body long, serpentine, without dermal arma- 
ture, so far as known. Vertebrz large and broad, with very prominent zygapo- 
physes and moderate neural spines; ribs large, convex.” 
M. MAcRURUS, Cope. 
M. WHEATLEYI, Cope. 
Locality. Coal-measures, Linton, Columbiana County, Ohio. 
References. Cope, Proc. Acad. Nat, Sci. Philadelphia, 1868, p. 220.—Jd. Synop- 
sis, p. 20.—Id. Supplement, p. 3. , 
Oéstocephalus, Cope. 
See Urocorpytvs, p. 170. 
Orthosaurus, Barkas. 3 
The illustrative figure represents a skull of Zoxomma. It is considered by Mr. 
Barkas a distinct genus of true Reptiles. 
O. PACHYCEPHALUS, Barkas. 
Locality. Low-Main Coal-Shale, Northumberland. 
References. Barkas, Coal-measure Paleontology, pp. 61, 102 [1873].—Atlas of 
Carboniferous Fossils, t. viii. figs. 183, 184, 185, t. x. fig. 282 [1873]. 
Osteophorus, Von Meyer. 
The upper surface only of the skull is known from an imperfect natural cast. ‘“‘ The 
total length of the skull amounts to 207 millims., the breadth to 274 millims. The 
length, as far as the hinder margin of the parietal tract, measures little more than 
the breadth. The orbits lie in the posterior half of the skull, nearer the middle 
than the hinder end; they are nearly circular, and not noticeably oblique in posi- 
tion; their transverse diameter is to the longitudinal dimension as 2 to 3. The 
external nasal foramina are more distant from the anterior end of the skull than 
from the external margin; they are somewhat less distant from each other than 
the orbits, while the distance between the nasal foramina and the orbits is about 
