24 TRANSACTIONS OF THE WAGNER FREE 



7. Perhaps the most interesting of the Peace Creek fossils are a number 

 of dermal plates of several species of the giant, armadillo-like Glyptodonts, 

 heretofore chiefly known from their remains found in the quaternary forma- 

 tions of South America. 



Five specimens submitted to my examination by Mr. Willcox, and two 

 others by Mr. Meigs, resemble so closely two similar ones from bone cav- 

 erns of Brazil, represented by Dr. Lund, and described by him under the 

 name of Chlaniydotheruiin Humboldtii^''' that it is not improbable they may 

 have belonged to the same species. They are also exceedingly like a num- 

 ber of similar specimens recently observed by me in the collection of the 

 British Museum and labelled with the same name, from the caves of Minas 

 Garaes, Brazil. Four of the Peace Creek specimens are represented in fig- 

 ures 3-6, plate IV. Five of the plates are variably hexahedral in the outline 

 of their breadth as exemplified in figs. 3, 6, one is petagonal, fig. 5, and the 

 other oblong quadrate, as seen in fig. 4. The thinnest hexagonal plate, 

 nearly uniform, is 8 mm. thick ; three other hexagonal plates, nearly alike in 

 thickness in different parts, are from 9 to 10 mm. thick ; the pentagonal 

 plate is from 7 to 13 mm. thick; and the oblong quadrate plate is 7.5 mm. 

 thick at one extremity and 1 1 mm. at the other. The hexagonal plate of 

 fig. 3 is the thickest, and measures from 11 to 16 mm. 



The exterior surface of the plates to within 3 to 5 mm. of the borders 

 is elevated and is everywhere more or less porous. The elevated portion 

 of the surface is somewhat depressed concentrically, but rises in a variable 

 low, elliptical eminence centrally. The borders of the plates are rugged, 

 and the under surface is slightly concave and exhibits a few perforations. 



The hexagonal plate, figure 3, is 49 mm. in its greatest breadth ; an- 

 other is 55 mm.; that of fig. 6 is 48 mm. ; and another is 45 mm. The 

 pentagonal plate, fig. 5, is 44 mm. broad; and the oblong quadrate one, fig. 

 4, is 55 mm. in its greater and 29 mm. in its smaller breadth. 



Since writing the foregoing, Mr. Willcox has submitted to my examina- 

 tion a collection of twenty-eight additional plates, collected in Peace Creek 

 and presented by Mr. T. S. Moorhead. Most of the plates accord with 

 those already described, but several are different. One of them is penta- 

 hedral, oblong, 55 mm. in its greater and 36 mm. in its smaller breadth. 

 One, probably a marginal plate, is pentahedral, with an angular border above 

 and a convex border below. Another, represented in fig. 12, plate V., 

 probably a marginal plate, is pentahedral, angular at the upper border and 

 convex below, and with its exterior produced in a conical eminence with 

 the apex directed downward. Its breadth is 36 mm., its height about the 

 same, and its thickness to the apex of the conical eminence 22 mm. 



Of fifteen hexahedral plates, the largest is 52 mm. in its greatest breadth, 

 35 mm. in its smallest breadth and 15 mm. in thickness ; the smallest is 42 



* Danske Vidensk. Selskab., Al'hand., 1841, taf. XI. 



