532 ALLIS. (Vou. II. 
and is faintly indicated in Fig. 1. The dorsal outline of this 
raised portion curves downward, leaving a semi-transparent space 
in front of it, between it and the hind edge of the cerebellum. 
Its curved surface forms an angle behind with the curved sur- 
face of the yolk, the line of the angle extending backward and 
upward from the hind edge of the opercular opening to the 
anterior end of the line of depression between the dorsal and 
ventral muscle segments of the body. At the angle formed by 
these two lines of depression, at some distance behind the 
supratemporal line, the lateral line begins, as does also the 
accessory lateral line. 
In specimens less than a day old, or even in those a little 
older, the lines or regions supplied by different nerves are dis- 
tinctly separate in picro-sulphuric preparations, but in chro- 
mic acid ones much less so, particularly when first killed in 
the vapor of osmic. In such specimens the infra-orbital line 
is somewhat continuous throughout its length. In fishes two 
and one-half days old this appearance is still more marked, 
as shown in Fig. 1, which is drawn from a chromic acid 
preparation. The sense-organs of the different lines in this 
specimen are not yet sufficiently developed to show on the 
surface; but the raised whitish lines, which indicate the 
positions of the cords of cells along which they arise, are 
strongly marked. The line of the supra-orbital canal is con- 
tinuous with that of the anterior dorsal pit line, and widely 
separated from the infra-orbital at the point where later the 
anastomosis with it will take place. Both ends of the line are 
enlarged where, according to the theory of Beard and others, it 
is pushing its way through the surrounding indifferent epithelial 
cells. The infra-orbital line is continuous throughout its length, 
and continuous with the lateral line which extends beyond the 
pectoral fin nearly to the level of the hind edge of the yolk. 
The accessory lateral line, which has just begun to develop, 
starts from the lateral line immediately behind the line of 
the supratemporal commissure, and is pushing backward 
through the surrounding cells exactly as the lateral line does. 
The ends of both these lines are enlarged, that of the lateral 
line sometimes forming a large and prominent swelling. The 
dorsal body line has not yet appeared. The posterior dorsal 
pit line of the head is continuous at an angle with the line 
