528 MR. A. S. WOODWARD ON [ Dec. 7, 
imperfect fragments are already represented by remains as complete 
as can be expected in a fossil state; and such remains being now 
forthcoming in the case of the remarkable Selachian, Squaloraja 
polyspondyla, it is proposed once more to bring this interesting 
form before the notice of zoologists. 
The first scientific account of the genus and species under consi- 
deration was communicated by Dr. H. Riley to the Geological 
Society in 1833, and subsequently published, with one slight modi- 
fication, in that Society’s ‘Transactions’*. A fine specimen in 
the Bristol Museum, displaying the head and vertebral column, with 
obscure fragments of the appendicular skeleton, formed the subject 
of this memoir, and notwithstanding the author’s limited means of 
comparison, he rightly recognized its affinities both with the true 
Sharks and the Rays, and expressed the circumstance in its generic 
name. Riley, however, misinterpreted the snout and rostral spine, 
regarding these as jaws, and originally suggesting the specific name 
of dolichognatha in allusion to their elongated shape; but Agassiz 
pointed out to him the error in time for correction in an appended 
note (J, c. p. 85), and the distinguished author of the ‘ Poissons 
Fossiles’ again figured and described the specimen in one of the 
later parts of his third volume*. Agassiz, indeed, was already 
acquainted with portions of the vertebral column and dermal 
tubercles of the fish, and had enumerated these in his preliminary 
manuscript notes under the name of Spinacorhinus polyspondylus ; 
but Riley’s prior description necessitated the adoption of the generic 
title Squaloraja, though his withdrawal of ‘ dolichognatha’ allowed 
the Agassizian specific name to be retained. 
But although Agassiz’s extensive acquaintance with the Selachian 
order enabled him to throw further light upon the Liassic genus, 
and point out its remarkable resemblances to the Pristiophoridze, he 
still failed to comprehend the precise nature of the curious snout, 
and it was left to Mr. William Davies, of the British Museum, with 
still more materials at his disposal, to offer a complete explanation. 
Tn an important paper in the ‘Geclogical Magazine’ for April 1872°, 
he pointed out that the uppermost rostral prolongation was a true 
spine, homologous with the frontal spine of the male Chimeroid 
Ischyodus orthorhinus, then made known by Sir Philip Egerton ; 
and he further demonstrated the absence of the appendage in some 
individuals, which were naturally regarded as females. Davies, 
moreover, added some notes on the vertebral column, and Hasse has 
more recently * published an account of the structure of the vertebrae 
‘in great detail. 
1H. Riley, “On the Saualoraja,” Trans. Geol. Soc. [2] vol. v. 1833, pp. 83- 
88, pl. iv. 
2 L. Agassiz, ‘Recherches sur les Poissons Fossiles, vol. iii. p, 379, pls. 42, 
43. 
3 W. Davies, ‘On the Rostral Prolongations of Sgualoraja polyspondyla, 
Ag.,” Geol. Mag. vol. ix. (1872) pp. 145-150, pl. iv. 
4 0. Hasse, “ Einige seltene palaontologische Funde,” Palwontographiea, 
yol. xxxi. (1885) p. 4, pl. i. figs. 2, 3. 
