British Associution Reports. 565 
igneous rocks he regarded as sometimes contemporaneous with the 
metamorphic action, having taken place into fissures and chasms in 
the crust while depressed and still in a heated state, as shown by the 
coarsely crystalline structure of many of these rocks at their line-of 
contact with those among which they have been injected, and in 
small granitic and other veins. In other cases, however, their pos- 
teriority in age was clearly shown by the opposite of these conditions. 
TV.—On a Heap or Hyzopus Dezazecurr. By E. C. H. Day, F.G.S. 
A HEAD of Hybodus Delabechei, Charlesworth, in the posses- 
sion of the author, has upon it in sité four of the cephalic 
spines first described, from a single specimen (and with the type of 
this species of Hybodus), by Charlesworth in 1839. Similar spines 
were subsequently described by Agassiz as teeth, and upon these 
supposed teeth that author founded a new genus of Hybodonts, which 
he named ‘ Sphenonchus.’ From the present specimen it is however 
clear, that these so-called teeth, or spines, are simply dermal scutes, 
such as are common in the Ray family, but not, as far as the author 
is aware, found upon any recent Shark. These scutes are placed, 
two on each side of the head, the anterior upon the post-orbital pro- 
cesses, the posterior upon the post-auditory processes, or hinder 
angles of the skull. The suggestion hazarded by Charlesworth, and 
provisionally supported by the author in a former paper, that these 
developments were analogous to the curious apparatus upon the 
head of the males of Chimeeroid fishes, therefore falls entirely to the 
ground, and we have indicated to us instead a slight but interesting 
character of resemblance to a distinct family of Plagiostomous fishes, 
the Ratide. But the composite character of this extinct family is 
shown in other points, as the author infers from the char structure 
and position of the dorsal spines, &c., that the Hybodonts were 
allied to the Chimeroids as well as to the Cestracionts and the Squa- 
Joids, and that therefore the fossil group, of which Hybodus and 
Acrodus may be taken as types, was intermediate in its zoological 
position, between the two existing orders of Plagiostomi and Holo- 
cephah. In conclusion, the author drew attention to the coincidence 
between the past occurrence of Hybodus in the Jurassic age, and the 
occurrence at present of its nearest allies, the genera Cestracion 
and Callorhynchus, in, and almost restricted to, those Australasian 
seas in which are preserved to us so many traces of Mesozoic life. 
V.—REMARKS ON THE DRIFT IN A PART OF WARWICKSHIRE, AND ON THE EVIDENCE 
OF GLACIAL ACTION WHICH IT AFFoRDS. By the Rey. P. B. Bropm, M.A., F.G.S. 
HE extent and character of the low level drift round Warwick 
and Leamington and along the valley of the Avon was first 
described, containing in places the usual Mammalian remains, but 
no flint implements had yet been detected. Of older date, belonging 
to the Glacial period, was an extensive deposit of drift occupying 
the high table land over an area of from six to twelve miles, NNW. 
and W. of Warwick. Rounded pebbles and boulders of various sizes 
