5 and 6. Type specimen of Mazonerpeton longicaudatum Moodie. × 1.
7. A copy of Cope's drawing of the type specimen of Amphibamus grandiceps Cope. The original was destroyed by fire. × 3.
The tail impression is more acuminate than in Micrerpeton, but shows the same structures as in that form, i.e., the lateral lines which have already been mentioned. Micrerpeton was a more rapid swimmer than the present form on account of the greater development of the tail.
The second specimen of the species (No. 802, Yale Museum) shows much the same character as the specimen already described, except that there are impressions of small, blunt teeth on the mandible. The two humeri and the femur of the left side are preserved and the interclavicle is represented by an identical impression, as in the first-described specimen. The tail impression, though similar in form, does not exhibit so much of the structure of the lateral lines ([fig. 15, B]).
The matter of especial interest in connection with this second specimen is the remarkably perfect preservation of the alimentary canal, which is entire, except for the very anterior end of the œsophagus. The posterior portion of the œsophagus, which measures 3.5 mm., is clearly preserved. Its anterior end is thrown around posteriorly and indicates that this end was loosened after death and became displaced before fossilization. The length preserved may represent the entire œsophagus. The œsophagus is constricted before it enters the stomach, which shows the usual curvature found in modern salamanders. The stomach measures 6 mm. in length by 2 mm. in breadth, and consists of a single enlargement as in the modern Amblystoma punctatum. It increases in size somewhat toward the pyloric end and then very gradually constricts to the pylorus. Three divisions of the small intestine can be seen. The most anterior one, corresponding to the duodenum, is segmented, as though the intestine had been filled with food before interment. The remainder of the intestine, corresponding to the ilium, is looped in the form of two figures 8 which are superimposed, with the upper portions of the 8 at right angles to each other. The rectum is clearly discernible, though its lower portion is somewhat obscured by having the lower part of the upper loop of the intestine lying over it. The anus lies at a distance of 1.5 mm. posterior to the transverse line from, the upper end of the femur, and is quite well back on the tail, as in modern salamanders. In this specimen also occur two oval bodies which may be identified as the lower ends of the oviducts, thus indicating, in all probability, that the animal was a female.
Fig. 14. Mazon Creek Amphibia.
A. Third specimen of Eumicrerpeton parvum Moodie, which exhibits the alimentary canal well preserved. × 2. Original in United States National Museum. a, anus; f, femur; h, humerus; ic, interclavicle; in, intestine; m, mandible; or, orbit; st, stomach; t, tibia and fibula.