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Show 1868.] DEVELOPMENT OF T H E SALMON. 253 nearly equal size, I have placed alongside the dimensions of specimens in the British-Museum collection. Unfortunately for perfect exactness of corresponding measurements, mine have been taken in tenths of an inch, while Dr. Giinther's are sixteenths, eighths, and quarters of an inch. Notwithstanding this difference in fractions, the eye is able to follow the lines of resemblance, or otherwise. Specimens in British Museum. No. 1. a. b. Total length 6*5 6| 7\ Length of the head 1*4 \fa^ \fa Distance between end of snout and eye 0*3 s s Diameter of the eye 0*3 _L Length of maxillary bone 0*6 fa Length of base of dorsal 0*9 Greatest height of dorsal 1*2 Length of pectoral 1*2 Distance between root of pectoral and root of ventral 1*6 . . •'• Length of ventral fin 3*1 Distance between root of ventral and origin of anal fin 1*2 Length of anal fin . 0*8 A\S regards the internal anatomy of the specimen No. 1, of which the bodily measurements are given above, the following points were noted :-The csecal tubes were from 18 to 50 in number; I state both of these numbers because, although counted several times, there was difficulty, 49 being counted once, 48 a second time, and 50 a third. Thev were small and not well developed ; greatest length of a single one 0*3 inch. The intestine beyond the cseci measured barely 3 inches long. Testes moderately developed, 2\ inches long, milt flowed freely on being handled. Air-bladder large, long, single, and tapering behind. The vertebrae are 59 in number. After having described our specimen, it still remains to say whether it is a Salmon or not. If not a true Salmo salar, then one would expect it be some other well-known form of the genus Salmo. Now upon this point there is some diversity of opinion. Mr. Buckland and Mr. Bartlett aver it is, and that the whole of the brood which I have referred to as having been hatched in February 1863 are true Salmon. This view I have been myself inclined to adopt; but the opinion of Dr. Giinther, than whom I know not a more scientific ichthyologist, has in some respects made me waver respect-in°* a decision/ On the other hand, it has strengthened my belief that the arrest of the growth of Salmon when retained in fresh water is a physiological fact, perfectly compatible with what we already know connected with the life-development of the Salmon. Those who have regarded our specimens as Salmon have done so, first, because of their history ; secondly, from their external markings and other outward anatomical resemblances to Salmon |