St 



\i:\V REPTILES AND STEGOCEPHALIANS. 



The second typo is small, ranging from 1 cm. to as much as 7, in extreme cases, 

 in length. They show very perfectly the spiral nature of the coprolite; two very good 

 specimens are shown in figure 33 a and b. It seems probable that these are the coprolites 



Fia. 33. 



A and B. Two coprolites showing trace of the spiral valve. X 1. 



(' and I). Two coprolites showing the longitudinal ridges. XL 



E. Figure of a tooth of an unknown form, No. 7506, U. of Mich. XL 



of the Dipnoan fish of the region, but in the light of the great number of the coprolites 

 it is strange that not more of the skeleton of the fish has been found; only two teeth and 

 no other parts of the skeleton have been found. 1 



The third type of coprolite is very different from the other two. These range from 

 2.5 to 7 cm. in length. They are all somewhat curved, sometimes approaching a cres- 

 cent ic form. In many, especially of the smaller coprolites of this type, the outer side of 

 the curve is marked 'by deep and regular grooves very evenly spaced (fig. 33 c). This 

 is so striking that when the first fragment of one was found it was suspected that it 

 represented the surface of a Cephalopod shell. In most of the larger coprolites of this 

 type the markings are very obscure or wanting, but the curved form is always character- 

 istic. In the larger forms there is frequently an additional part of the coprolite which 

 lit- over the end as a cap or cloak (fig. 33 d). It is impossible to associate this type of 

 coprolite with any definite group of animals; the only suggestion that can be made is 

 that in many amphibians the distal portion of the rectum is thrown into parallel linear 

 folds — just such an arrangement as would make linear markings upon the fcecal mass. 



INCERTiE SEDIS. 



A small fragment of a jaw contains a very singularly shaped tooth which the author 

 has been unable to identify, or even to determine its relationships. As shown in figure 

 33 e, the tooth is elongate oval in section, with the greatest diameter parallel to the 

 length of the jaw. In general outline it is reminiscent of the teeth of the Permo- 

 ( iarboniferous reptile JJiadecles, but the upper edge is contracted, slightly concave antero- 

 poeteriorly, and has a narrow, flat surface, slightly inclined toward the outer (?) side. 

 The outer (?) side ot the tooth is slightly concave, and there is a swelling at the base 

 Bad then a sharp contraction. The tooth is without root and attached directly to the bone. 

 The base of a second tooth shows the rather spongy character of the base (fig. 33 e). 



•Cav I I Occasional Papers of tin- Museum of Zoology, University of Michigan, No. 101, Apr. 9, 1921. 



