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



vein passing upon the right, and in some a distinct bulging of the yolk-sac occurs in 

 front of the globule. Moreover, during the extremely cold weather of the period, 

 the globule was often thrust outward at this part. The head of the embryo 

 presents a remarkably truncate appearance, the snout, indeed, projecting less than the 

 large eyes, when viewed from the dorsum (as in the figure just mentioned). A decided 

 difference exists, therefore, in this respect, when compared with the young salmon, in 

 which the long yolk-sac trends downward and backward, whereas in this form the 

 yolk-sac is globular, and is directed downward and forward. 



This being, so far as known, the largest British marine Teleostean larva yet 

 described, its comparison with that of the salmon, the largest fresh-water form, is 

 naturally suggested. Many points of contrast are at once presented ; thus the difference 

 in coloration is marked, for while both have pigment in the eyes, the yolk in Anarrhichas 

 is straw-coloured and inconspicuous, whereas in the salmon it is rendered conspicuous by 

 the deep reddish-orange colour of the oleaginous globules. The latter become grouped, 

 again, in masses in the upper region of the yolk-sac; whereas in Anarrhichas the 

 single, large, somewhat lenticular globule maintains a constant position in front. The 

 general pinkish tint of the newly-hatched salmon, further, is more pronounced. The 

 external features of the wolf -fish also present less differentiation, for the marginal fin is 

 simple and continuous, the tail is lanceolate, and the pectoral fins at this stage are much 

 smaller. The head, moreover, is very different, for when viewed from the dorsum 

 (PI. XX. fig. 5), the large eyes, as already noted, project even further than the snout ; 

 while in the salmon the snout protrudes considerably beyond the eyes. 



In a newly-hatched example about a week later (1st February) the tail is somewhat 

 bluntly lanceolate, the ventral lobe being more distinct than the dorsal (PI. XX. fig. 1), 

 and the notochord passes in a straight line backward to terminate in a point. A slight 

 wrinkle of the margin of the delicate caudal membrane occasionally marks this termina- 

 tion. The notochord here is finely cellular, the size of the cells increasing anteriorly. 

 The neurochord presents a marked diminution just above the margin of the vascular loop 

 beneath the notochord. The membranous tail-fin has fine striae (embryonic rays, 

 produced by delicate fibres), and is cellulo-granular. The aorta, in coursing back- 

 ward, gives off a twig inferiorly, which diverges from the ventral surface of the noto- 

 chord, and then ends in a slender vessel passing almost to the tip of the chorda, and 

 returns as a recurrent vein. The ventral twig of the aorta splits into two loops, which 

 ramify over a limited area (see PI. XX. fig. 1), and then joins the caudal vein by a single 

 trunk. This condition diverges from that in the salmon at the same stage, but a com- 

 parison between the two forms may be conveniently reserved till a later period. The 

 circulation in the caudal region attains but a slight development in the wolf-fish at this 

 stage, whereas the vitelline vessels are as fully developed as in more advanced 

 larvae. 



Vitelline Circulation at the Period of Hatching. — We have already mentioned that 

 on emerging a large vitelline vein passes on the right side of the larval trunk, collecting 



