On the British Species of Asterolepide. 285 
of those which are only apparent or fallacious—still retain 
three British species of Pterichthys, namely, P. Mulleri, P. 
productus, and P. oblongus. 
BOTHRIOLEPIS. 
In my paper already quoted I included five British species, 
those being B. major, Agassiz; B. hydrophilus, Agassiz; B. 
macrocephalus, Egerton; and two others which I described 
as new, namely, B. giganteus, from Alves, near Elgin, and 
B. obesus, from the Jedburgh district. 
The last of these, B. obesus, Traq., is a perfectly “good 
species,” but I have seen reason to change my mind as 
regards B. giganteus. The characters by which I formerly 
distinguished it from B. major, Ag., were two, besides its 
large size, namely, the greater coarseness of the ornament 
on the plates, and the arm not being proportionally so long 
and slender as I supposed it to be in B. major. Here the 
examination of a considerable amount of additional material 
brings out two interesting facts. 
1. The occurrence of smaller specimens in the Alves 
quarries, in which the ornament is finer than in the larger 
ones, and, in fact, indistinguishable from that of the plates 
of B. major from Scat Craig. This led me to compare the 
ornament in young and adult specimens of B. Canadensis, 
Whiteaves, with the result of finding that the coarseness of 
the sculpture of the plates increased with the size of the 
specimen. It is therefore not possible to distinguish B. 
giganteus from B. major by such a character. 
2. Comparison of such elements as have hitherto occurred 
of the pectoral limb of B. giganteus from Alves, with the 
corresponding parts in B. major from Scat Craig, of which I 
have seen many since my paper of 1888 was written, fails to 
bring out any distinguishing peculiarity. Whence, then, did 
I derive the idea that this organ in major was peculiarly 
elongated? By assuming that the remains occurring at 
the Heads of Ayr, and which indeed show this peculiarity, 
belonged to the same species. 
It is therefore not the species from Alves which is new, 
but that from the Heads of Ayr; so that while the former 
VOL, XI. oO 
