No. 2.] AMPHIUMA MEANS. 393 



side of AmpJiiitma than on the right. The left dorsal mass is 

 also considerably stronger than the right. This asymmetry is 

 probably due to the manner in which the animal lies coiled, 

 though I have not had opportunity to demonstrate that fact. 

 The obliquus internus muscle is composed of fibres taking 

 origin from the tendons of the transverse processes, and ex- 

 tending obliquely anteriorly between the inscriptiones tendineae. 

 External to this muscular plate lies the obliquus externus, readily 

 recognized, as the fibres extend obliquely posteriorly between 

 the inscriptiones. As the fibres of these two oblique muscles 

 approach the ventral line they gradually change their direction, 

 becoming finally parallel with the axis of the animal, and thus 

 form the rectus abdominis. In all other Amphibians except 

 AmpJiiimia this muscle is continuous over the ventral line. 

 Its fibres are completely interrupted by the inscriptiones. An- 

 teriorly it is continuous with the thoracico-hyoideus and omo- 

 humero-maxillaris. Posteriorly it is attached to the pelvic 

 elements, but continues as the ventral caudal muscle. Thus 

 it will be noticed that the trunk and head muscles of Amphiuma 

 are more highly specialized than those of other Urodeles, while 

 the limb muscles are less specialized. 



Digestive System. 



The food of this Urodele consists of crayfish, small teleosts, 

 and other similar aquatic life. The lining membrane of the 

 buccal cavity is tough and smooth, but its continuation into 

 the pharyngeal and oesophageal region is loose and somewhat 

 corrugated longitudinally. On the ventral side are numerous 

 ciliated columnar cells. The stomach is a slight enlargement 

 of the oesophagus, beginning at a distance behind the shoulder 

 girdle, equal to the distance of that girdle from the tip of the 

 nose. The mucous lining of the stomach is thrown into small 

 longitudinal ridges in the anterior portion of the organ, these 

 ridges increasing in prominence as they extend posteriorly. 

 The walls of the stomach in its anterior parts are but little 

 thicker than those of the oesophagus, but posteriorly they 

 become nearly twice as heavy. The length of the stomach is 



