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 7f inches in length, by 4f inches in 

 its greatest breadth. 



7. Orthagoriscus Mola. (Schneider.) The Short 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 

 Red 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- 



