PROCEEDINGS OF GEOLOGICAL SOCILTIES. 
47 
those more characteristic parts upon which the conclusions of the author of the 
paper, respecting the structure and affinities of Stayonohpis, are based. 
They were, — 1. Dermal scutes ; "2. Vertebrae ; 3. Ril)S ; 4. Bones of the ex- 
tremities ; 5. Bones of the pectoral arch ; and 6. A natural cast of a mandible with 
teeth. The dermal scutes are all characterized by an anterior smooth facet, over- 
hipped by the preceding scute, and by the peculiar sculpture of their outer surface, 
which exhibits deep, distinct, round, or oval pits, so arranged as to a])pear to 
radiate from a connnon centre. Of these scutes there are two kinds, the flat and 
angulated. By a careful comparison with the dermal armour of ancient and 
modern crocodilian reptiles, it was shown that every peculiarity of the scutes of 
Stagonolepis co\dd find its parallel in t\\os& oi Crocodilus or Teicosawus ; the flat 
scutes resembling the ventral armour of the latter ; the angulated scutes the 
dorsal armour of the former genus. 
An unexpected verification of the justice of this determination was furnished by 
a natural cast of a considerable portion of the caudal region of StcKjonolepis, con- 
sisting of no less than seven vertel)ra>, enclosed within the corresponding series of 
dermal scutes. Of these, the dorsal set were angulated ; the ventral, fiat. 
It would appear that the anterior dorsal scutes attained a very considerable 
thickness, while the more posterior scutes were widest — attaining more than five 
inches in breadth in some instances. The vertebrae described were all studied 
from natural casts, and belonged to the caudal, sacral, and anterior dorsal series. 
Tliese vertebrae are, in their leading features, similar to those of Teleosamians ; 
tlie obliquity of the articular faces of the centra, so characteristic of the vertebrae 
of Stagonolepis, being, as the author of the paper pointed out, a very common 
character of Teleosanrian, and even of modern Crocodilian, vertebra*. Of the 
sacral vertebrae, only a natural cast of the posterior face of the second had been 
oljtamed ; but it was sufticient to demonstrate the wholly crocodilian characters of 
this region in Stagonolepis. 
The dorsal vertebrae present a remarkable peculiarity in the strong upward, 
outward, and backward inclination of the transverse processes, and in the size of 
the facet for the head of the rib. The vertebrse thus acquires a Dinosaurian 
character ; but no ^reat weight was attached to this circumstance, as the amount 
of upward inclination of the transverse processes of the anterior dorsal vertebne 
varies greatly in both Crocod'dia and Enaliosauria. 
The ribs have well-marked and distinct capitula and tubercida ; and the scapula 
is extremely like that of a crocodile. The femur, though somewhat thick in pro- 
portion to its length, and though its articular extrennties present such a peculiarly 
eroded appearance as to lead to the belief that they were covered with thick car- 
tilaginous epiphyses, is also completely crocodilian in its characters. 
The natural cast of the manthble is remarkable for the great length and sub- 
cylindrical contour of the teeth, the apices of which are slightly recurved. The 
surface of the tooth is marked by numerous close-set longitudinal grooves, which 
all terminate at a short distance from the smooth apex. It would ai)pear that the 
teeth contained large pulp-cavities, and that each was set in a deep and distinct 
alveolus. Notwithstanding their sjiecial peculiarities, these teeth might in many 
respects be compared with those of the Teleosauria. 
A metatarsal or metacarpal bone, reproduced from a natural cast, was shown to 
be similar to that of a crocodile, but so much shorter in proportion to its thickness 
as to indicate an altogether shorter and broader foot. The cast of an ungual 
phalanx, on the other hand, proves that Stagmiolepis had long and taper claws. 
Thus far the resemblances with the Crocodilia are, on the whole, very close ; 
but the characters of a coracoid obtained from Lossiemouth, separate Stagonolepis 
from all known recent and fossil Crocodilia. It is, in fact, a lacertian coracoid, 
veiy similar to that of Hylceosaurus. 
In sunnniug up the evidence tlius brought forward as to the affinities of Stagono- 
lepis, the author, after comparing it with the oldest known Reptilia, exjjressed his 
oi)inion that the peculiar characters of this ancient reptile separate it as widely 
from the mesozoic Repitilia hitherto discovered, as these are separated, from the 
cainozoic members of the same gi'oup, — in fact, it widely diverges from all known 
recent and fossil forms, and throws no clear light on the age of the deposit in 
which it occurs. 
