408 PALEONTOLOGY OF OHIO. 



of considerably smaller size than the limb just mentioned. They are but 

 doubtfully these elements. 



Length of proximal element, .004 m. ; length of two distal elements, 

 .0038. 



COLOSTEUS PAUCIEADIATUS, Cope. 

 Transactions American Philosophical Society, April, 1874. 



Established on median and lateral pectoral plates of perhaps two indi- 

 viduals, the latter of which I formerly referred to the C. scutellatus. It 

 belonged to a larger specimen than either of the preceding, and is dis- 

 tinguished by the paucity and weakness of its ridges. These are en- 

 tirely transverse on the posterior third of the length, but are interrupt- 

 ed and irregular on the median portion ; the anterior third is almost 

 smooth. 



The lateral shield is little larger than the largest of G. scutellatus, but 

 resembles the median plate in its low and distant carinffi. An arc 

 drawn at about the middle of a radial line from the outer angle crosses 

 about eleven of these ridges ; in C. scutellatus twenty exist in the same 

 space. 



The median plate is pyriform, with the posterior angle little prolonged, 

 and the anterior not narrowed and rather short. The lateral shield is a 

 right-angled triangle, the inner or thin edge concave posteriorly; the 

 posterior convex. 



Length of median, 0.063 m. ; width of median, .040; width of lateral 

 behind, .0242 ; length of lateral, .045. 



