294 PROCEEDINGS OF THE AMERICAN ACADEMY 



The young Ctenolabrus at a very early age assume the peculiar 

 slanting of the body which the older fish take specially when feeding 

 or when coming up to examine any object. 



MOTELLA ARGEXTEA, Rhein. 



(Plate VII. Plate VIH. figs. 1-3.) 



The youngest specimen of this species I have seen (Plate VII. 

 fig. 1) measured 4"'™ in length. It was remarkable for the compara- 

 tively strong coloring for so young a stage. The head dorsal and 

 ventral muscular lines, as well as the sides of the stomach, are of 

 a dark dirty yellow. The pectorals are large and transparent, but 

 the ventrals, already well developed, are of a dark maroon color. 

 The lower part of the eye is light blue, the pupil of a dark crimson. 

 About half way between the tail and pectorals there are two large 

 pigment cells, one in the dorsal, the other in the ventral side of the 

 notochord. A smaller cell indicates the position where the embry- 

 onic caudal fin rays are forming. 



There are three pigment cells on the brain, the largest in front, two 

 smaller ones at the extremity of the snout, one on the lower and one on 

 the upper jaw, with a still smaller cell at the base of the operculum. 

 Four to five larger cells form a black edge to the upper side of the 

 stomach. In a somewhat older stage (Plate VII. fig. 2) the principal 

 differences consist in the greater size of the pectorals, the larger 

 ventrals, the increase in size of the chromatophores on the head and 

 stomach, and the greater elongation of the snout. Seen from above 

 (Plate VII. fig. 3) the ventrals appear like wings proportionally as 

 large as the pectorals of the young Flying-Fish. In a young fish 

 measuring T"'" in length (Plate VII. fig. 4) the pectorals have in- 

 creased but little in size since the preceding stage. The ventrals are 

 nearly one third the length of the fish. The head, quite rounded 

 above, is proportionally larger, and the body much wider and less 

 elongate than in the younger stages (Plate VII. figs. 1-3). 



The chromatophores are more numerous in the upper part of the 

 head and on the upper part of the stomach, while the single cell of 

 the dorsal region half way to the tail has increased to a large patch 

 of chromatophores, and forms in this stage the largest accumulation of 

 pigment cells. The permanent rays of the caudal fin are well 

 advanced, and at the base of each is placed a minute pigment spot. 

 The permanent rays of the dorsal and anal are also commencing to 



