554 MB. E. W. L. HOLT ON THE [J Ulie 21, 



A specimen of 13*5 mm. does not differ greatly from the last. 

 It was evidently fully clad, in life, with dark-coloured scales. The 

 radial formula is D. 11 or 12, A. 15 or 16. I can see no certain 

 indication that any rays have been entirely lost. 



A specimen of 12 mm. (fig. 2) has the radial formula D. 14 ca., 

 A. 18. There are no signs of scales. The photophores are in- 

 complete, but such as are present correspond in position to those 

 of fig. 1 and of S. glacialis. A low wrinkled ridge of skin occurs 

 along the back from the nape to the first dorsal fin. The pro- 

 portions of the head, eye, and snout are as 25 ( = 3'5 mm.), 7, 6. 

 There is thus a further reduction in the eye and increase in the 

 snout as compared with the 14*5 mm. stage ; but I think it will 

 be conceded that the two specimens (figs. 1 and 2) are specifically 

 identical. A vertical from the commencement of the anal passes 

 a little behind the front of the dorsal. The base of the adipose is 

 more extended than in the last stage. 



Fig. 3 shows a specimen of 11'5 mm. The radial formula is 

 D. 14 ca.,A. 18 c#., the rays being rather indistinct in the posterior 

 parts of the fin. The adipose is continued forward by a fold of 

 membrane, beset with numerous embryonic rays, reaching nearly 

 to the base of the dorsal, but its permanent region is indicated 

 by an interneural prominence of the dorsal contour. The 

 proportions of head, eye, and snout are as 25 ( = 3 mm.), 7, 6, 

 a further reduction of the eye being thus indicated. The 

 specimen is drawn in a rather oblique position. Viewed in exact 

 profile, the top of the eye does not quite reach the cephalic contour. 

 No photophores appear to be fully developed, but one is indicated 

 at the lower extremity of the preoperculum, while some pigment 

 on the mandibles seems to be representative of others. A patch of 

 pigment occurs on the isthmus. Except in the eyes no other 

 external pigment is visible ; but internally a black mass in the 

 postero-dorsal part of the abdominal cavity, visible when the 

 specimen is clarified, is probably associated with the air-bladder. 

 The greater part of the abdominal cavity is occupied by a volumi- 

 nous intestinal tract beset with transverse ridges. The liver is 

 comparatively small, and occurs below the basal part of the 

 pectorals. Posterior to this line the whole cavity, so far as I can 

 see, is occupied by the intestine, which passes by a slight con- 

 striction into the pyriform rectum. The mouth is smaller than 

 in the more advanced stages, a condition familiar in the ontogeny 

 of the Salmon. 



The most remarkable feature of the larva is a large bladder-like 

 expansion of the skin of the dorsum between the head and the 

 dorsal fin. In the present condition of the specimen it is some- 

 what collapsed and flattened, its edges projecting from the upper 

 part of the sides. Pigs. 3 and 4 show this structure from different 

 points of view, the true dorsal contour being indicated in the 

 profile drawing by a dotted line. It is obviously identical with the 

 wrinkled fold already noted in the 12 mm. stage, which is the 

 degeneration of what is evidently a larval organ. In the specimen, 



