DEVELOPMENT AND LIFE-HISTORIES OF TELEOSTEAN FISHES. 859 



than in the adult, the basal region being massive and muscular, while the distal forms 

 a broad fan-shaped fin still having embryonic rays. It would appear that the relative 

 sizes of the basal and the distal regions of this fin vary according to the different stages 

 of the young fishes, the basal being especially large in the early larval condition, and 

 gradually diminishing as the older stages are reached. These form most efficient organs 

 during the purely pelagic life of such fishes. The branchial arches show small rounded 

 papillae (representing the branchial lamellae). The otocysts are large and prominent. 



This form seems to vary considerably in length in the subsequent stages, thus, e.g., 

 on the 28th April, some, though further advanced in general structure, were shorter than 

 in the earlier condition. The snout shows less of the previous disproportion — the pre- 

 maxillary region having grown outward so as to project almost as much as the mandible. 

 The tail forms a symmetrical fan-shaped organ, the base presenting a straight vertical 

 line (hypural), while the upper edge is pointed, from the tip of the notochord. The 

 marginal fin is prominent from the vent inferiorly, and somewhat in front of this dorsally, 

 rising a little in each case in the middle, and diminishing toward the tail, which it 

 joins. Permanent rays occur in both, the anterior and posterior ends, however, being 

 devoid of them. The black pigment forms in front of the anus two lateral rows of large 

 spots, and a median more continuous series as far as the anus ; while behind the latter a 

 row of smaller specks exists on each side of the median line. Just in front of the 

 pectorals a black pigment-bar occurs on each side. 



At 12 mm. in length (also in April) the body has considerably increased in depth, 

 while the tail-fin is now more elongated, and presents a median notch. The fin-rays in the 

 dorsal extend distinctly forward to a line running upward from the anus, and less clearly 

 for some distance in front of this. In the anal fin the rays reach the anus. These fins 

 are at this stage distinctly separated from the caudal, and the base of the latter has a 

 double crescent at the edge of the hypurals. The oblique bars of pigment in front of the 

 pectorals, and the black pigment-spots along the ventral line are well marked, especially 

 in front of the anus. The anal has now a double row of minute black pigment-specks 

 at its base, a feature apparently coincident with the development of the rays. The 

 mandible slightly projects beyond the premaxillse. On 28th April they ranged from 

 9 to 14 mm. in length. Like other food-fishes, this species is subject to the attacks of 

 parasitic young Caligi. 



The next stage in the collection was procured in the mid- water net on the 5 th May 

 1887, at the depth of 4 fathoms on 6 fathom ground, and they reached from 17 to 18 

 mm. in length, though some were less. The shape and arrangement of the pigment-spots 

 generally agree with those mentioned in the last stage. The tail still shows two hypural 

 crescents — with a dotted line of pigment running from the dorsal to the ventral edge. 

 The rays of the dorsal fin, though short, can be traced forward to a point midway 

 between the anus and the pectorals. The eyes are still proportionally large, and the 

 mandible projects in front of the premaxillse. The branchiae have simple papillae, with 

 at most traces of crenations at the sides, and the gill-rakers are developing. The same 



