OF ARTS AND SCIENCES. 293 



innumerable variations in coloring noticed in the adult Ctenolabrus. 

 During a single season at Nahant, the late Professor Agassiz had no 

 less than sixty colored sketches made of specimens of this species, 

 measuring from three to four inches in length, illustrating differences 

 in the coloring or markings. In younger stages, when the young 

 Ctenolabrus measures not more than 15™"" in length, I have found 

 fully as great a variety in the types of coloration as among the adult ; 

 the principal types of coloring varying fi-om a perfectly uniform light 

 green tint to a mottled and banded pattern, which recalls far more 

 Julis than the usual pattern of design and coloring found in our 

 Ctenolabrus. The next stage figured (Plate XY. fig. 1) is but slightly 

 more advanced than Plate XIV. fig. 5 ; it belongs to the light-colored 

 type. The principal differences to be noticed are the nearly complete 

 disappearance of the caudal embryonic fold and the formation of a 

 rudimentary anterior spiny part of the dorsal. In a young Ctenolabrus 

 (Plate XV. fig, 2) measuring 11™™ in length, this anterior part of the 

 dorsal is somewhat more developed ; the urostyle is much smaller. 

 This specimen belonged to a type of coloring of which the adult has 

 patches of darker color along the dorsal and ventral lines, these 

 patches also extending over the anal and dorsal fins. The darker 

 chromatophores are black, those of the dorsal fin and along the dorsal 

 are of a light-brown color, and the whole upper part of the body and 

 head is colored a brilliant yellow. In a young Ctenolabrus measuring 

 15™™ in length the anterior part of the dorsal has greatly increased 

 in height, the posterior ends of the dorsal and anal have become 

 rounded, and there is no trace of the rudimentary caudal embryonic 

 fin. Young specimens of the same length were either uniformly 

 covered by closely packed brownish or black chromatophores on a 

 reddish-brown or greenish background, or else the darker chromato- 

 phores were arranged in bands, slanting from the median line towards 

 the tail, with irregular patches at the base of the dorsal fin and along 

 the dorsal side, or else they were of the pattern figured here (Plate 

 XV. fig. 3) upon a light yellowish background. 



In a somewhat more advanced stage (Plate XV. fig. 4) of about 

 the same length as Plate XV. fig. 3, the body and head of the young 

 Ctenolabrus have become quite compact, the fins resemble in outline 

 those of the adult, and the young Ctenolabrus has practically assumed 

 the principal characteristic features of the older and larger fish. 

 Fishes in the stages of Plate XV. figs. 2-4, are still pelagic, though 

 many of them can be caught in the eel-grass or kelp along with the 

 older fishes. 



