Notices of Memoirs—L. Dollo—On Mosasaurus, ete. 519 
9. The shapes of the hills of this range, produced by weathering, 
are not those usually visible in regions of volcanic, but rather of 
metamorphic rocks. 
The rocks which furnished the basis for the above conclusions are 
all, or nearly all, alteration-products. In some cases they appeared 
to be the results of a second, third, or even greater number of meta- 
morphoses, some of their constituents seeming to pass through cycles 
of change, ending in the mineral with which the alteration began 
after a number of intermediate stages. The rocks are Diorites, with 
Epidote, Porphyritic Dolerites, which resemble and have been taken 
for Syenites; Garnet rock; Actinolite; Felsite and Orthofelsite 
Porphyry, like that of the South Mountain of South-eastern Pennsyl- 
vania, of St. David’s Head in Wales, and elsewhere. ‘T’o these are 
added Pyrite and iron ores. Copper and manganese ores are not 
rare, but their relations to the rocks under consideration have not 
been made out. 
TV.—Sur te Genre Huctasres. By Lovurs Dotto. Ann. Soe. 
Géol. du Nord, vol. xv. (1888), pp. 114-122. 
DETAILED discussion results in the conclusion that to the 
synonymy of the Chelonian Huclastes (Cope, 1867), must be 
relegated the generic names Lytoloma (Cope, 1871), Puppigerus 
(Cope, 1871), Glossochelys (Seeley, 1871), Pachyrhynchus (Dollo, 
1886), and Erquelinnesia (Dollo, 1887), The genus is thus defined 
as follows :—Skull very broad and flat. Supratemporal fossee com- 
pletely closed by a bony roof. Orbits more or less directed upwards. 
Nasals distinct. A lateral temporal notch well marked. Palatine 
expansion triangular, very thick, and almost on the level of the 
alveolar border. Vomer very long, extending towards the occiput, 
and separating the submaxillaries and the palatines for a consider- 
able distance. Posterior nares situated much nearer the occiput 
than in the Chelonide. Palatal vacuities for the passage of the 
temporal muscles extraordinarily broad. Mandible massive, with 
a very long symphysis. Carapace rounded behind. The Chalk 
fossil shown in fig. 4, plate vii. a of Owen’s “Mon. Foss. Rept. Cret. 
Form.” (Mon. Pal. Soc. 1851) is considered to belong to Huclastes ; 
and the genus is also represented in the Upper Cretaceous of the 
United States, and the Lower Hocene of Belgium and England. 
V.—Sur Le Crane pes Mosasaurtens. By Lovurs Dotno. Bull. 
Scientifique France et Belgique, 1888, pp. 1-11, pl. 1. 
\HE fine double plate accompanying this paper is occupied by a 
profile view of the skull of Hainosaurus and another of a less com- 
plete skull of Mosasaurus, each with an osteological explanation, and 
the two placed together for comparison. M. Dollo also investigates 
an interesting minute point in the osteology of the Mosasaurian 
skull, namely, the significance of the shallow rounded pit upon the 
proximal half of the quadrate bone. The feature was first noticed 
by Prof. E. D. Cope, who considered that it probably “received the 
extremity of an osseous or cartilaginous styloid stapes;” and Sir 
Richard Owen afterwards suggested that it might have received 
