MOODIE: MAZON CREEK, ILL., SHALES. 335 
more clearly characters which are distinct from Micrerpeton, 
the genus to which the present form is most nearly related. 
The present specimen is almost as perfectly preserved. as 
was the specimen of Micrerpeton caudatum Moodie. When 
the nodule containing the fossil was received the tail was em- 
bedded in matrix, but by careful use of chisel and hammer it 
was possible to lay bare the whole tail, the tip of which ends 
on the very edge of the nodule. This was at once perceived 
to be precisely similar to that of the above-described specimens. 
The skull structure, the intermediate position of the pineal 
foramen, the epiotic notch and the shape of the skull are so 
exactly similar to those of Huwmicrerpeton parvum that the 
specimen was unhesitatingly referred to that species. 
Most interestingly, too, the present specimen has the ali- 
mentary canal preserved almost as perfectly as in the other 
two specimens; so that the three specimens of this species 
now known show the alimentary canal. The present speci- 
men is, however, much more developed than the other two, if 
we may judge from the relative sizes. There is not the slight- 
est trace of branchie in any of the specimens. The matrix 
does not preserve the skeletal elements as well as does the 
hard dolomite from Saxony, in which Doctor Credner found 
such excellently preserved branchie. 
The present specimen is nearly half again as long as the 
smallest of the above-described specimens, and the skull is 
proportionately longer and wider. There is preserved also an 
impression of the anterior edge of both clavicles, as has been 
described for the Yale specimens; no other portion of the 
pectoral girdle is preserved. The right humerus is imper- 
fectly preserved, as is also the right femur and tibia; other 
than these the fossil is merely an impression. 
The skull is so nearly like what has been described for the 
Yale specimens that additional description is unnecessary. 
The pineal foramen is quite large, and lies on a line which 
cuts the orbits into equal longitudinal parts. The interorbital 
space is about equal to the long diameter of the orbit, as in 
the Yale specimens. Traces of sclerotic plates are observed 
in the left orbit, but they are quite imperfect. 
The alimentary canal is unlike that of the Yale specimens, 
in that the INTESTINE is longer and much more convoluted. It 
lies in five longitudinal folds and ends in an enlarged cloaca, 
