846 PROFESSOR W. C. M 'IN TOSH AND MR E. E. PRINCE ON 



The next phase consists in the strengthening of the abdominal wall ventrally, the 

 increase in the distribution of the pigment, the left side still remaining slightly speckled, 

 while the right is densely coloured ; the more distinct grouping of the pigment in 

 " touches" in the fins both dorsally and ventrally, and in the progress of the right eye 

 towards the left. The marked notch behind the angle of the mandible, and the elevation 

 of the head behind the right eye, are also noteworthy features. When the right eye 

 mounts on the dorsum, the dorsal fin forms a high arch over it, and the body has con- 

 siderably increased in depth in comparison with its length. A specimen about 9 mm. in 

 total length has a depth of 6 mm. Besides the " touches " of pigment on the fins, a 

 few minute blacks points are scattered over the left surface — the right being covered 

 with minute dots almost as densely as before. 



A subsequent stage to the foregoing is shown in PI. XIX. fig. 1, but no specimen in 

 our collection affords the intermediate or transition-features so as to ensure certainty by 

 continuity of stages. The occurrence of the pigment-touches in the dorsal and anal fins, 

 however, and their character, the general shape of the body, and the appearance of the 

 head, support the probability that they are stages of the same species. None show 

 traces of the spines, although the right eye has now reached the edge of the face. The 

 eyes appear to be larger. Though some examples are no longer, they are somewhat 

 better developed, a feature common in such fishes, certain individuals often reaching an 

 advanced stage more rapidly than others which are even larger. In such an example as 

 figured in PI. XIX. fig. 1, which was 9*8 mm. in total length and 7 mm. in total 

 breadth, the tail measures 2*5 mm., so that the length from the snout to the base of the 

 tail is nearly equal to the total breadth. The right or ventral surface is pale, with the 

 exception of a few irregular black specks and streaks, while the dorsum is streaked across 

 with black pigment-bands, which have a remarkably regular arrangement, the touches in 

 both dorsal and ventral fins being joined by intermediate streaks, the head and abdomen 

 only showing scattered points. The under surface is quite pale, and thus contrasts with 

 the minutely speckled right surface of the specimen in the earlier stage. The dorsal 

 and anal fins have long rays toward their posterior border, and the body of the fish 

 acquires a somewhat quadrate form. The ventrals still show the pigment-streaks, and 

 thus are in uniformity with the anal in a lateral view. Moreover, a characteristic 

 larval cuticular spine appears at the posterior part of the head, above the opercular 

 margin, and somewhat in front of a vertical line running up from the pectoral, while 

 a smaller spine projects a short distance beneath. Both right and left spines are well 

 marked in another example a few mm. longer, and which shows a similar coloration. 

 They are probably protective spines, since they disappear as the fishes grow older. Their 

 appearance on both sides, after the right eye is at the edge, indicates the possibility that, 

 for some time, the fish may occasionally resume the vertical position in swimming. 

 Further, the presence of a young Caligus fixed to the right side supports this view. A 

 specimen, 20 mm. long, captured at the surface, shows the right eye just on the ridge, 

 with the dorsal fin close to its posterior border. 



