DEVELOPMENT AND LIFE-HISTORIES OF TELEOSTEAN FISHES. 809 



During the following days the black pigment continues to increase, especially at the 

 base of the abdomen. At first the radiate corpuscles are separate, but they subsequently 

 anastomose and form dense patches. 



16th day (PL X. fig. 2). — The great size of the pectoral fins (pf) is the most 

 prominent feature at this stage. They are in constant motion, flapping to and fro like a 

 pair of fans, and the pigment (pt) on their surface is largely developed. The yellowish 

 yolk has shrunk very much, and forms an irregular mass in the pectoral region, the oil- 

 globule, apparently undiminished in size, still occupying a posterior position. A large 

 vacant space (ss) is left in front of the rectal tract, and a similar large space (ss) occurs in 

 front of the yolk. The snout is much elongated, and viewed from above is like a 

 truncated cone just as in the adult gurnard. A feature of moment is the comparatively 

 motionless condition of the mandible (mn). The marginal fin (ef) shows no differentia- 

 tion into definite fin-areas ; it is, as compared with the breadth of the body, now 

 proportionately narrower. As above noted, the pectorals (pf PL X. fig. 2a) are the 

 most noteworthy feature, standing out almost at right angles to the trunk, and so well 

 developed that, viewed obliquely, the young fish resembles very strikingly Pegasus natans. 

 Under a lens the yellowish pigment is seen to be confined chiefly to the head, pectorals, 

 and yolk-area. A few corpuscles occur along the margin of the dorsal fin in front, and 

 a few also on the tail ; but the body has fewer of them than previously, finely branched 

 black corpuscles alone being present. A later stage (PL X. fig. 3), about three weeks 

 after emerging from the egg, exhibits much the same features — a chitinous bar being 

 prominent in the premaxillary region. The next stage under observation was procured, 

 along with a large number of others, while in the Fishery Board tender " Garland," and 

 the specimens were slightly larger than the last stage described, viz., about 6 mm. in 

 length. They clearly were the young of the same year, as they were obtained at the close 

 of summer, viz., 31st August. The great size of the head generally, as well as of the 

 eyes and brain, was characteristic, and especially the broad scoop-shaped snout with the 

 median " bite." Behind the head the pendulous abdomen projected like the yolk-sac 

 (now almost wholly absorbed) of the earlier stages. The stomach, in fact, was found to be 

 greatly distended with minute Copepoda, which form the staple food at this time. The 

 pectorals are even larger than in the previous stage ; while the marginal fin with its 

 embryonic rays continues into the tail fin, which shows the notochord as a median 

 slightly tapered axis. From this axis the rays below slant downward and backward, 

 while those above lean upward and backward. Those coming from the tip of the 

 notochord are short. The ventral rays are larger, and a granular opaque tract below the 

 chorda probably indicates the site of the future hypurals. No cartilaginous rays are 

 present. The marked downward projection of the angle of the jaw, and the lean tapering 

 body behind the massive abdominal region are noteworthy features. As the specimens, 

 on account of their extreme delicacy, were injured by the pressure of the water against the 

 net, it was necessary at once to consign them to alcohol, and their colours were thus 

 more or less lost. Large stellate pigment-spots could, however, be distinguished along 



VOL. XXXV. PAET III. (NO. 19). 6 L 



