258 Proceedings of the Royal Physical Society. 
6. Rhombus Hirtus. (Yarrel.) Muller's Topknot. 
I am indebted to my friend Mr Dick for a fine specimen 
of this curious fish. It was taken in the Pentland Firth 
off Thurso. The under-side of the specimen is perfectly 
smooth. It measures 7| inches in length, by 4f inches in 
its greatest breadth. 
7. Orthagoriscus Mola. (Sclmeider.) The SJiort Sun Fish. 
8. Lamna Cornubica. (Cuvier.) The Porbeagle. 
Seldom a herring fishing passes without specimens of both 
being captured in the nets, &c. Last year the sun fish was 
rather abundant. It is often lifted by its fins into boats 
when basking in the sun. 
As it is not my intention now to give a list of all the 
fishes observed by me on this coast, I shall conclude, by way 
of tail-piece, with a few words on some of the last joints of 
the vertebral column of the salmon tribe, for they, like the 
tail of Luath's dog, have an upward curl." Some months 
since I was eating for breakfast a trout, when, to my sur- 
prise, I found that it had a crooked tip to its vertebral 
column. Since then I have found this to be constant in 
trout of all sizes, whether from rivers, lochs, or the sea ; and 
that salmon, from the smolt to old age, have it also, as 
may be seen by the tails herewith sent. The three last 
joints of the vertebral column take a turn towards the edge 
of the upper lobe of the tail, the tip of the last joint is 
pointed, and from it a strong cartilaginous cord is continued 
into the upper lobe, and thus these fishes have a true hetero- 
cercal tail. I refrain from further remarks on the other 
peculiarities connected with these turned-up joints, or offer- 
ing any comparison with the heterocercal fish of the Old 
Ked Sandstone, being now only concerned for the turn in 
the recent fish. Not finding any information on the subject 
in the various works on fishes that I have access to, I for- 
warded a series of tails to Professor Huxley. I believe he 
had observed this peculiarity, but had laid it aside : he is 
now working at it ; and although I know that the subject 
is in excellent hands, I am desirous of laying it before my 
brother members, in order that, should it already be a well- 
known fact, they may instruct me where to search for infor- 
