1901.] NATURAL SCIENCES OF PHILADELPHIA. 339 



Mouth. — Moderately large and capacious. No asperities what- 

 ever upou the walls aud teeth absent. No buccal flaps. A broad 

 tongue, bluntly rounded aud hardly free in front. 



Pharynx. — Rather large, long and compressed, and also destitute 

 of asperities. The apertures of spiracles are placed superior and 

 anterior to the first gill-opening. The gill-openings are 5 in num- 

 ber, the first the largest and the others gradually decreasing in size 

 until the last, which is the smallest or shortest. They all commu- 

 nicate with the branchial chamber, forming 4 separate or free 

 branchial arches and one adnate to the posterior part of the 

 pharynx. The four free branchial arches are furnished with the 

 usual complement of gill-filaments, distributed along their outer 

 edges. No gill -filaments upou the last branchial arch. Upon the 

 inner anterior and posterior edges of the branchial arches are short, 

 fleshy, filamentous gill rakers. They are not very numerous, not 

 A- the length of the longest gill-filaments, and longest medianlv. 

 The branchial arches themselves seem rather broad. 



CEsophagus. — The enteric canal is now somewhat consiricted, 

 jDersisting posteriorly until under the posterior portion of the air- 

 bladder, when it turns and is produced anteriorly until posterior to 

 the pericardial cavity. Here it forms a somewhat exaggerated 

 condition known as the stomach. 



The oesophagus is connected by a large tube, though short, with 

 the air-bladder. This is placed a short distance from the pharynx 

 and upon the first or upper division of the oesophagus. 



Sto)iiach. — Rather small and apparently not very capacious or 

 distensible. The walls are considerably thickened, the tissue being 

 muscular. After this the pyloric region is marked by a large, 

 compressed and rounded sac, which is nearly as large as the stomach 

 itself. 



Intestine. — The duodenum persists first posteriorly, then runs 

 forward a short distance, after which the colon is formed. Its 

 walls are porous and not muscular. 



The colon is furnished with a spiral valve and no rectal gland is 

 present. The rectum is well developed. 



Liver. — Large, anterior and superior, and bilobed. 



Ryder ^ says under Acijyenser brevirostris Le Sueur: "How 

 much more extensive than the Delaware River its range may be I 



1 Bull. U. S, Fish Comm., VIII, 1888, p. 236. ~ 



