56 PHYSOSTOMI. 



by Dr. Giinther to between fifty-nine and sixty, and among the repnted seven 

 non-migratory forms to between fifty-six and sixty. Occasionally two small 

 vertebras take the place of one large one, as if a division had occurred ; while 

 in others may be observed an abnormally large one, as if two had coalesced, 

 as shown by the normal number of hemal spines for two bones being present. 

 Dr. Giinther instances a case " where three vertebra? were united," and Cobbold 

 " of the coalescence of numerous vertebral centra." In a fish wherein these 

 bones normally number about sixty, an extreme variation of five (especially 

 as such has not been proved to be constant) does not by itself appear to be 

 beyond what might be anticipated in a single species ; and inconstant variations 

 would scarcely justify the creation of a new specific name for the reception of 

 such, unless conjoined to other circumstances. Among a number of common 

 trout which I captured at Colesbourne, on the Cotswold Hills in Gloucestershire, 

 some had fifty-seven, others fifty-eight vertebrae ; while in a few received from 

 Cardiganshire I ascertained that this variation extended to between fifty-seven 

 and sixty. As the extreme limits of variation recorded in this country among 

 the common trout have been between fifty-six and sixty, and as these examples of 

 an undoubted single species captured in one locality gave from fifty-seven to 

 sixty, it would seem to be a rash conclusion to formulate species of Salmonidce 

 solely consequent upon an enumeration of the number of vertebras as ascertained 

 in a few specimens. Only one fact appears to be rendered exceedingly probable, 

 which is, that anadromous forms generally possess an excess of one or two 

 vertebras over such as are more strictly residents only in fresh waters. 



2. The number of coecal appendages. — This has been adduced as a character which 

 may materially aid in discriminating a species. If the list of British Salmones already 

 referred to is examined, it will be seen that these appendages in the common salmon 

 may vary between fifty-one and seventy-seven, and in the Loch Leven trout between 

 forty-nine to ninety. (It must be noticed that personally I have observed larger 

 variations than are here recorded, but I have purposely restricted myself to the 

 numbers given in the British Museum catalogue.) These cceea are capable of 

 distension, of subdivision, of amalgamation between two or more, or of being longer 

 or shorter than is commonly the case. The difficulty does not appear in 

 discovering variations, but in determining within what fixed number they exist 

 in a given species. At Colesbourne, I found in the common brook trout already 

 referred to, from thirty-four to thirty-nine coecal appendages, and up to forty- 

 four in the Cardiganshire examples, the same as in S.ferox. .The question forces 

 itself on our consideration whether in any form of trout the number of these 

 appendages are persistent or inconstant, and whether change of climate or food 

 may occasion any variation. Here I must refer to the results obtained from the 

 examination of trout that have been reared in distant localities, but descended 

 from British breeds. Mr. Arthur (Transactions of the Otago Institute, July 

 9. 1878) refers to the stock of common trout " which were liberated in our 

 streams in November, 1869, and from these and their descendants the ova for 

 stocking the rivers in Otago have been obtained." The original ova came from 

 Tasmania, the trout existing there being the proceeds from three batches of eggs 

 supplied from England through the kind offices of Mr. Francis Francis and 

 Mr. Frank Buckland. They were obtained from streams in Buckinghamshire and 

 Hampshire, and reputed to be the eggs of the common brook trout. The number 

 of coecal appendages is recorded in six instances from Otago, and they varied 

 from forty-three to fifty-four, whereas the limits in the British race is restricted 

 in the British Museum catalogue to between thirty-three and forty-seven. Even 

 were these hybrids, and their existence was pointed out by Willughby, the 

 number of their coecal appendages would still exceed, by at least seven, any 

 recorded among the British non-migratory forms, except the Loch Leven trout, 

 and are consequently an excellent instance of the inconstancy of their number. 

 Here I must refer to Mr. Senior's observations on these trout, now in a wild state, 

 as he has observed them in some parts of Tasmania. Owing to the abundance of 

 winged insects, beetles, grasshoppers, &c, it seldom rises at the artificial fly ; when 

 hooked it has lost the energy of its ancestors, for after one rush if baffled it 



