LATERAL LINE OF AMIA. 509 
spond to the pit organs in Amia. They lie at the bottoms of 
flask-shaped epidermal pits, each of which contains a single 
organ. The external opening of the pit is about the size of the 
exposed upper end of the organ, and the organ which is smaller 
than, but similar to, those found in the lateral canals does not 
come in contact with the sides of the pit. They are found in 
lines or irregular groups on the head, and on the body in four 
lines or series of lines, a dorsal line, two accessory lateral lines, 
one immediately above and one immediately below the lateral 
canal, and a ventral line. The pits of the ventral line and those 
of the dorsal accessory line are all connected by small longi- 
tudinal canals formed in the deeper layers of the epidermis, and 
those of the ventral accessory line that are formed on a single 
segment of the body are similarly connected. The organs of 
the dorsal body line are not so connected; but canals extend 
transversely on either side of them, and end blindly in the 
epidermis, often branching toward the end. These epidermal 
canals have not been described in other fishes. They agree 
exactly in position with the cords of cells connecting the pit 
organs in Amia; and if these cords should be replaced by 
canals, or canals should be formed in them by deliquescence 
or otherwise, as the lateral canals themselves are formed in 
Selachians, the arrangement described by Emory would arise. 
The artificial separation of the cord from the overlying epidermal 
cells would probably produce a somewhat similar appearance. 
5. Surface Sense-organs. 
Under the name Terminal Buds Merkel includes a large class 
of organs, which, in Amia, always come to a level with or pro- 
ject slightly beyond the outer surface of the membrane in which 
they lie. They are found in great numbers on the external 
surface of the head, including the operculum, gular plate, and 
branchiostegal rays. They also extend on the top of the body 
as far as the dorsal fin; but behind this, and along the sides and 
belly, none could be found by surface examinations of the adult 
or by sections in young specimens, and none were found on any 
of the fins. They are also found in the mouth and branchial 
cavities. 
In the adult they are scattered irregularly over the surfaces 
