ME. F. DAT ON THE LOCH-LETEN TROUT. 
87 
At Cowley, in Gloucestershire, one fertile male had 62, one 
which was sterile 52. Among females, varying in length from 12 
to 22 inches, the number of these appendages in 7 examples of 
fertile fish averaged about 58, derived from the following numbers 
— 66, 64, 62, 59, 57, 55, 45 ; while one large female from Loch 
Leven had 47. As a rule these cseca appear to be larger in females 
than in males, while in one of the latter a single one of these 
tubes was abnormally shortened near the pylorus. 
The foregoing figures show a variation at Howietoun in the 
number of these appendages, ranging from 48 to 82 in male fish, 
and from 45 to 66 among female fish ; while in one male which 
was fertile, examined in Gloucestershire, there were 62, and in 
another, not so well fed, from the same locality, and sterile, there 
were 52. In only one is the number seen to approach 90 (82) 
as given by Dr. Gunther, and with that exception 75 was the 
largest number counted, and from that dow r n to 45, clearly 
showing that this is an unstable character, prone to change, 
and consequently unsuitable for discriminating species. Also 
that, aw r ay from Loch Leven, these appendages have diminished 
in number, and still more so in examples from the ova hatched 
at Guildford and reared in Gloucestershire, where the smallest 
fish were sterile and had the fewest of these appendages. As to 
the diameter of the caeca, the difference was not apparent, except 
so far as I have mentioned above. 
Possibly the number of the caecal appendages may, under certain 
cii’cumstances, be found of value in ascertaining whether the food 
on which the fish subsist is of such a nature that they will thrive 
or deteriorate. 
If these appendages decrease when the fish are transferred 
to other localities, it may be asked if instances can be adduced 
where they have ever been found to increase in trout when 
removed to better feeding-grounds or improved conditions of 
life*. The eggs sent from the brook-trout of Hampshire and 
Buckinghamshire by Mr. Prank Buckland and Mr. Prancis 
Prancis to Tasmania have developed into a large race, in which 
the caecal pylori seem to have reached the normal number of 52, 
shoving a considerable augmentation, and again proving the 
number of these organs to be inconstaut. 
Bespecting the vomerine teeth being in a single series in Loeh- 
* Since this paper was read (viz. in March 1887) young rainbow-trout 
(Salmo iridens), 22 months old, raised at Howietoun, have been examined. In 
California, whence the eggs were received, these fish are said to possess about 40 
caecal appendages; in one dissected at Howietoun I found 71. 
