1388 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
that of the Hag’s, is a satisfactory transition type, has 
long been recognised. From the study of the olfactory 
organ and its associated parts (infra p. 142) I entirely 
agree with Huxley’s belief. Concerning the comparison 
which I herein institute between the less numerous 
cartilages which support the Lamprey’s sucking mouth, 
and the more numerous ones, having essentially the same 
relationships, in the Hags and Callorhynchus, the only 
course open, in the absence of observations upon the 
development of the latter animals, is to enquire if argu- 
ment from structural analogy will or will not bear this 
out? I would direct attention to the ossification of the 
hypo-hyal of the Teleostei from two centres instead of one 
as elsewhere—to the inconstancy in number and rela- 
tionships of the ossific centres of the body of the hyoid 
generally, *—-to the great variability in number and disposi- 
tion of the splenial elements of the mandible—to the 
ereat variation In number and relationships of the labial 
cartilages of Klasmobranchst—and, more especially, to 
the fact that whereas in Polyodon{ the palato quadrate 
cartilages are simple, and remote except for their sym- 
physial anterior borders, being altogether normal in 
character, in the allied Acipenseroids they meet above the 
roof of the mouth, and become secondarily fragmented in 
a manner as unparalleled as it is extraordinary. § 
The above cited facts appear to me to answer the 
question in the affirmative. There are involved in a 
comparison of the palatoquadrates of the Sturiones just 
* cf. espec. the Batrachia, Parker, Phil. Trans., 1881, part I. 
+I have often wondered that in Rhina (Squatina), where these simulate 
the arrangement of the mandibular arch and hyomandibular they have not 
been claimed by some ingenious person as a corresponding pre-oral series. 
tef. Bridge. Phil. Trans., 1878, pp. 701—702, and Pl. 57. 
§ Parker and Howes, Phil. Trans., 1882, p. 117. 
