530 MR. A. 8. WOODWARD ON [Dec. 7, 
of the vertebral column. But the detached spines would appear to 
afford evidence of two or more forms as yet unrecognized, and the 
small example, no. VIII., is particularly distinct. It is very possible, 
indeed, that when more specimens of the genus are available for 
study, the characters of the rostral appendage will enter promi- 
nently into the diagnosis of each species; but I only venture, on 
present evidence, to distinguish the possessor of the small spine no. 
VIII. (Plate LV. fig. 6), and this may be appropriately designated 
by the name of S. ¢enuispina. The fossil in question is separated 
from its homologue in the known species by its much more slender 
and acuminate shape, and possibly, though not certainly, by the 
slight concavity of the proximal half of its upper surface. 
During the investigation of these fossils I have had the privilege 
of discussing the subject with several zoological and paleontological 
friends, to whom I am indebted for some valuable suggestions noted 
in the following pages. I desire especially to return thanks to Prof. 
W. K. Parker, F.R.S., for much kind assistance in regard to the 
skull; to Mr. G. B. Howes, for a continuance of the help so freely 
given on previous occasions ; to Mr. G. A. Boulenger, for the facili- 
ties afforded in the study of the recent Seiachians under his care ; 
and to my senior colleague, Mr. William Davies, to whose earlier 
work reference is so frequently made in the sequel. 
ANATOMICAL DESCRIPTION. 
External Form.—Commencing the description with a brief notice 
of the general external form of Sgualoraja, attention may be first 
directed to the beautiful specimen no. I., represented in Plate LV. 
fig. 1. As the shape of the head had already led Agassiz and Davies 
to suspect, the proportions are found to be very similar to those of 
the living Pristiophorus. Assuming that about three centimetres 
are missing from the tail of the specimen, the snout will have 
occupied one quarter of the entire length of the animal. The body 
must have been but slightly compressed from above downwards, and 
the pectoral fins were undoubtedly free, having no connection with 
the head; the shoulder-girdle, however, is placed relatively nearer 
to the chondrocranium than is the case either in Pristiophorus or 
Pristis, though appearances are not improbably deceptive, owing to 
crushing during fossilization. It is impossible, of course, to deter- 
mine whether the gill-openings were ventral or lateral, and scarcely 
any traces of the branchial arches have been preserved. The 
pectoral fins, as usual, are much larger than the ventrals, and the 
tail is long and slender, without spine, as admirably shown in no. ILI. 
(fig. 7). Unfortunately, all sure indications of dorsal and caudal 
fins are wanting, thongh it is scarcely likely that these appendages 
were absent in the living fish. 
Dermal Structures*.—In regard to the integument and its appen- 
dages, the new fossils afford some interesting additional information. 
No less than eight rostral spines are now available for study ; and 
? The dentition will be more conyeniently treated in a later section, p. 534, 
