Holt — On the Eggs and Larvce of Teleosteans. 463 



Two days later (fig. 49) the yolk is still further reduced, and very few oil- 

 globules remain. The total length is now 2-38 mm., the increase being still 

 confined to the post- anal region. The mid-brain (ni. b.) is more prominent dorsally, 

 and the mouth {in.) forms a deep pit below the eyes. The lower jaw is short, and 

 downwardly directed. 



The otocysts are much larger. The gut is a little bent downwards in 

 the middle of its course, and the rectum (r.), except a very short distal 

 portion, is expanded and tubular. A considerable interval, due to the absorp- 

 tion of the yolk, now occurs between that structure and the rectum. The 

 pectorals (p-f.) have increased in size; they are fan-shaped, and their bases are 

 further forward than before, and have undergone a considerable rotation in the 

 usual direction. The arrangement of the pigment is somewhat altered. The 

 earliest pigment bar (p.b.) has been carried backwards with the elongation of the 

 post-anal region. In front of it are three large pectinate patches along the dorsum, 

 the most anterior lying above the anus. Similar ventral patches opposite the 

 two dorsal ones, almost form two anterior bars. The anterior bar noticed in the 

 larva of four days has disappeared. Large patches, varying in individuals, occur 

 along the dorsal fin near its margin, the largest being in the anterior region. 

 Lengthened patches occur along the ventral near its base, principally in the 

 posterior region. In the specimen figured the dorsal does not extend so far 

 forward as in the earlier stages shown. The pectorals are pigmented, and embry- 

 onic fin-rays have appeared in the caudal fin. 



In older stages (shown in figures 50 and 51) the prominence of the mid-brain 

 (m. b.) is still more marked; the heart is advanced, and the gut is longer and 

 slightly convoluted; the anus is perforate; and a long urocyst [u.) has appeared 

 behind the rectum. The pectoral fins are lobate and rayed. The otocysts (ot.) 

 are larger, and somewhat rectangular and inferiorly concave. They are now close 

 behind the eyes. There are no oil-globules left in the reduced yolk mass. A 

 marked angulation of the dorsal fin occurs behind the pectorals. 



The post-anal region of the trunk is very attenuated, and the marginal fins 

 are much expanded. 



Black pigment has commenced to appear in the eyes ; and further changes 

 have taken place in the arrangement of the yellow pigment. 



The total length is now 2"98 mm., the increase being still almost entirely 

 confined to the post-anal region. 



The development of the jaw apparatus is much advanced, the lower jaw (mic.) 

 projects boldly forward, and is freely moveable. The liyoid and branchial arches 

 are easily seen, but the latter are not as yet pectinate. The heart (/«.) is closed 

 and perfect. The gut is much lengthened and convoluted, and the liver (I.) is 

 seen as a lobe-shaped body in the anterior part of the abdomen. There is a 



