888 PROFESSOR W. C. M'INTOSH AND MR E. E. PRINCE ON 



is much increased, especially at first over the opercular region, and other parts of the head. 

 The " parr-marks " on the sides are eleven in number, though, from the close proximity 

 of several, they do not appear to be so numerous. They are not symmetrical on the sides, 

 the fourth being double on the left side, whereas it is the third that is so on the right in 

 the specimen examined. Along the dorsum the pigment is arranged in a double chain, 

 while the head shows an hour-glass pattern. The black spot on the operculum is well 

 marked. The tail laterally and posteriorly exhibits a brownish -pink hue from the presence 

 of the reddish pigment-corpuscles. These latter are likewise distributed on the general 

 surface of the body and on the dorsal fin. 



About a fortnight later the entire body is covered with pigment-corpuscles, which are 

 larger and more closely aggregated at the " parr-marks." Minute glistening granular 

 bodies also occur in various parts of the integument. The dorsum anteriorly has a con- 

 siderable member of pinkish-red corpuscles, giving it a reddish tint to the naked eye. 

 Small corpuscles of the same hue occur in the " fatty " fin, in which the vessels ramify 

 very plainly. 



Along the dorsum (behind the pectorals) are seven pigment-masses. The first, imme- 

 diately behind the pectorals, is large and distinct. The second, also distinct, is situated 

 at the anterior part of the dorsal fin, covering a space in front and a portion on each 

 side of the fin. The third has similar relations to the posterior part of the fin, besides 

 proceeding some distance behind it. An elongated and less defined mass follows, in front 

 of the " fatty " fin, and connected with a smaller patch at the anterior border of the fin, 

 which proceeds a short distance on either side. Eight fairly definite lateral bars are 

 present on the left side, with a less evident ninth bar at the tail. On the right, likewise 

 are nine, the sixth being placed a little behind the (posterior) margin of the dorsal fin, and 

 so elongated and large as to appear double or compound. The ventral surface is silvery 

 white, and the general colour of the back greenish. Scales are now present on the 

 dorsum, and mucus scraped from the surface is found to contain many flat nucleated cells 

 (epithelium) of a delicate transparent character, with a large granular nucleus, and one or 

 more nucleoli. 



The young salmon, about a month older, shows a little variation in the "parr-marks." 

 Thus, in some eleven occur on the left, while nine are present on the right side. The 

 dorsal pigment remains much the same as above described. A reddish tint is still observ- 

 able at the margin of the fins. The young fishes, however, differ somewhat in size and 

 colour, some being quite light, others very dark under the same conditions. In many 

 examples a large yellowish patch occurs in the posterior part of the cranial region, while 

 in front is a greenish-yellow area. The usual changes in tint, however, are observed on 

 removal from a darker to a lighter situation, except in sickly or apparently dying fishes. 

 The round glistening bodies composed of transparent granules are still abundant. 



The pigment of the two species mainly considered in the preceding pages offers a few 

 interesting features to which brief reference must now be made. 



The young wolf-fish is uniformly tinted, or at least exhibits no bars, in the stages up to 



