

149 — 



The lachrymal, in Peristedion, has a long, flat, spatula-shaped anterior portion, which forms 

 the preorbital process of the skull, and an equally long, but slender and tapering process-like posterior 

 portion. The spatula-shaped portion projects, its füll length, beyond the anterior end of the cranium; 

 and is marked with surface granulations on both its dorsal and ventral surfaces. It is traversed, 

 in a somewhat peculiar manner, by the main infraorbital eanal. This canal begins at a long groove 

 on the dorsal surface of the spatula-shaped portion of the bone, the groove beginning at the hind 

 end of that part of the bone, near its mesial edge, and from there running forward a short distance 

 parallel to the mesial edge of the bone. The hind end of the groove lies immediately antero-mesial to the 

 antero-lateral corner of the nasal bone, and hence immediately antero-mesial also to the first pore of 

 the supraorbital canal. The groove is covered, in the recent State, by a drum-head-like membrane 

 perforated by one or more small pores, and represents the first primary tube of the main infraorbital 

 canal. From there the canal runs forward to the anterior end of the bone, where it curves latero- 

 posteriorly and then runs backward to the hind end of the spatula-shaped portion of the bone. There 

 it leaves the bone, lateral to its posterior, process-like portion, to enter the second bone of the infra- 

 orbital series. On the ventral surface of the bone, three large oval openings lead into the canal, 

 each closed by a perforated drum-head-like membrane, these openings representing the 2nd., 3rd. 

 and 4th. primary tubes of the line. The 5th. tube of the line lies between the lachrymal and the 

 2nd. infraorbital bone, and it also opens on the ventral surface of the snout; the 6th. tube being the 

 first one to open on the dorso-lateral surface of the skull. This opening of these first five tubes of 

 the line, on the ventral surface of a portion of the snout of the fish, associated, as it is, with a 

 mouth that also lies on the ventral surface of the snout and is supplied with barbels, strongly recalls 

 the conditions found in Acipenser and Scaphyrhynchus. 



The process-like posterior portion of the lachrymal lies along the dorso-mesial edge of the 

 second infraorbital bone, over-lapping that bone internally. Its pointed posterior end passes beyond 

 the second bone and there rests upon the external surface of the dorso-mesial edge of the dermo- 

 ectopterygoid. The base of this posterior portion of the lachrymal is slightly grooved on its mesial 

 edge and this groove is continued forward along the mesial and anterior edges of a flat depression, 

 with a curved anterior edge, that lies on the ventral surface of the base of the anterior, spatula-shaped 

 portion of the bone. The groove and depression lodge the flattened maxillary process of the palatine 

 and a short adjoining portion of the slender body of that bone, the two bones being firmly bound 

 together. Posterior to this groove, the lachrymal and palatine are, for a short distance, not in direct 

 contact, a slit-like opening being left between them; this opening lying opposite the nasal pit and 

 lodging the lateral portion of the nasal sac. Posterior to this nasal opening the two bones again 

 come into contact, the rod-like hind end of the palatine lying in a narrow space between the lachrymal 



