892 PROFESSOR W. C. M‘INTOSH AND MR E. E. PRINCE ON 
and a similar prominence (pre-anal) corresponding to no structure in the adult fish, and 
not comparable to the first anal of the Gadide, occurs between the ventral and the anus.* 
When a week old, these portions, which correspond to the regions of the permanent fins, 
are denser, the other parts being very thin, and apparently undergoing absorption. 
The embryonic rays are now distinct. Meanwhile the blood-vessels begin to ramify 
in the “fatty” fin (Pl. XXVIII. fig. 3), and the capillaries in front and behind the 
primary series are on the ninth day increased; they soon, indeed, extend throughout the 
entire length of the fin. Several indications of true fin-rays occur in the first dorsal, and 
at the end of a fortnight the embryonic marginal fin has, to the naked eye, nearly 
disappeared, so that the permanent fins are more boldly marked. Pigment appears in 
both dorsal fins at the same period; while pale capillaries ramify in the anal fin, and 
stretch nearly to the tip. They probably also develop in the dorsal and ventral; but 
they were not seen. The marginal (embryonic) fin is now almost absorbed, except in 
the interval between the ventral fin and the anus. 
Between the fourth and fifth weeks, the dorsal and anal fins show the cartilaginous 
rays, while the membranous parts between them are widened and coloured by numerous 
yellow and brownish pigment-corpuscles. Thirteen rays occur in the dorsal, and the 
same number in the anal fin, and the interspinous elements produce wavy marks beyond 
the muscle-plates. Both fins have crenate borders, as in the tail at this period; while 
the adipose fin presents a fibrillated aspect, and has a network of fine blood-vessels. All 
the fins are proportionally larger than in the adult, as observed in the outline of an 
average specimen (Pl. XXII. figs. 10 and 11). In minute structure the dorsal and other 
fins already present most of the characters of the adult. Thus, at the anterior part of 
the dorsal, are two narrower and shorter rays, the first a simple spike, the second con- 
sisting of two which form a loop. At the base of the larger rays is a projecting median 
point, and the terminal process is long, and almost unciform. The pigment is chiefly 
placed on the cartilaginous rays. 
In considering the condition of the median fin-rays of these young fishes, it will be 
observed that on the thirteenth or fourteenth day the dorsal of the soft-rayed salmon 
corresponds nearly with the condition in the adult, but in the anal fin the number of rays on 
the tenth or the twelfth day, viz., thirteen, is in excess of the number in the adult. In this 
respect, however, it is doubtful how far authors in numbering the rays have anatomically 
examined the parts, or how much they have depended on external appearances. On the 
other hand, the osseous rays in the dorsal of the young wolf-fish seem, if Day be right, 
to be fewer than in the adult, viz., 71 as compared with 72 or 74 (Day), while the rays 
in the anal present a similar condition, viz., 44 in the young as against 45 to 46 in the 
adult. An examination, however, of the skeleton of a fine adult in the University 
Museum here shows that the number of the dorsal fin-rays exactly corresponds with that 
of the young forms just mentioned, and so with the ventral. There may be variation ; 
* The outlines of the fins of the young salmon seem to differ considerably from those of the larval Lochleven 
trout, as shown by Mr J. T. Cunninawanm, Trans. Roy. Soc. Ldin., vol. xxxiii. pl. i. fig. 4. 
