70 PROCEEDINGS OF THE AMERICAN ACADEMY 



with the lower part of the mouth cavity ; the embryonic fin has broad- 

 ened, and extends further along the back towards the head ; the mus- 

 cular bands surrounding the chorda are far better defined, and a few 

 black pigment spots have also made their appearance at the base of 

 the anal fin ; the eye has become more distinct, and the nostrils are 

 seen as elliptical pits close to the eye as in the earlier stage. 



On the third day, the young Lepidosteus, when seen in profile, has a 

 triangular yolk-bag (Plate II. fig. 13), greatly reduced in size from the 

 previous stage ; the whole body is covered with minute black pigment 

 cells, more numerous towards the head and along the dorsal side ; the 

 gill-covers are now large rectangular fiaps (see also Plate II. fig. 12), 

 and we find in this stage the first trace of the pectorals. These appear 

 at first at a distance from the body on the upper surface of the yolk- 

 bag (Plate II. fig. 12) as slight curlings of what we may call a lateral 

 fold, indicated by a spiral line on the upper part of the yolk-bag. 

 Seen in profile (Plate II. fig. 13), they stand up vertically, forming- 

 slight protuberances above the general surface of the yolk-bag. The 

 eyes are more prominent ; the whole snout has become more elon- 

 gated than in previous stages ; and the sucking-disk is more prominent 

 than in younger stages, — the individual suckers projecting frequently 

 far beyond the general outline of the edge of the sucker, when the 

 young fish holds to any surface to which it may firmly have attached 

 itself. The outline of the tail, or of the embryonic fins, has not 

 altered from the preceding stage. 



The young Garpikes would find it most inconvenient to move 

 about with the huge yolk-bag with which they are provided ; and 

 although when disturbed they are powerful swimmers, propelling 

 themselves much after the manner of tadpoles, by vigorous strokes of 

 the tail, yet they remain until much later in life nearly constantly 

 attached to the sides or bottom of the jars in which they are kept ; 

 and, if disturbed, will, after swimming round rapidly a few mo- 

 ments, hasten to attach themselves again to some suitable surface, 

 where they remain hanging motionless during the greater part of the 

 time till the yolk-bag has been completely resorbed. Their hold on 

 the sides of the jar was so strong that they would remain suspended 

 after the water had been lowered below the level to which they were 

 attached. 



Two days later, the yolk-bag has become still further reduced, espe- 

 cially under the gill-covers (Plate II. fig. 14) ; the trend of the head 

 also makes a larger angle with the axis ; the eyes have become more 

 prominent; the gill-covers have greatly lengthened (Plate II. fig. 15), 



