1915.] NATURAL SCIENCES OF PHILADELPHIA. 121 



The complete skull of a soft-shelled turtle, with cartilages of 

 mandibles still attached, was found on Billy's Island, June 19, 1912. 

 This skull agrees with Boulenger's short description" and in all 

 general features with Hegner's figure,^- and, while much weathered, 

 shows the bones and sutures in excellent shape. It is remarkable 

 for the high supraoccipital ridge (the two squamosal ridges being 

 damaged) and for the very flat temporal region. 



This skull measures 3f inches in length, 2| inches in wicUh, ^ inch 

 between eyes, diameter of sockets | inch, distance from orbital to 

 nasal opening f inch, length of lower mandible 2^ inches, width of 

 lower mandible at posterior angle 2| inches, height of lower mandible 

 at middle | inch, distance between orbit and auditory cavity f inch, 

 distance from orbit to margin of upper mandible | inch, maximum 

 height of head, including both mandibles, If inches. 



Several carapaces of Platypeltis ferox, much weathered and usually 

 more or less mutilated at the edges, were found on Billy's Island. 



Such a carapace shows the upper surface white and finely reticulate, 

 with pits prominent and the sutures distinct. Nine neural plates 

 are present, the anterior very broad and without corresponding 

 costals on either side (i.e., is a nuchal); in form rectangular, about 

 twice as long as wide. Seven costal plates on each side, parallel 

 and regular, and extending transversely across the carapace. The 

 marginal area appears brown and leathery, the plates fused. The 

 under surface of the carapace is smooth and yellow-white. The 

 ribs are prominent and imbedded in the plates of the carapace; 

 eight on each side, extending more or less radiately from the verte- 

 bral column. This column is likewise fused with the carapace and 

 presents nine vertebrae. One carapace with nine neural plates had 

 eight, not seven, pairs of costal plates, the last two pairs meeting 

 on the median line where the neurals are absent. These carapaces 

 are about 9 inches in length, 8 inches in breadth and 2 inches in 

 height. 



A good series of young soft-shelled turtles were collected in the 

 swamp and preserved. These range in size from If to 3|- inches in 

 length and show plainly the brilliant, characteristic markings of the 

 carapace, especially when the shells are wet. The smallest specimens 

 agree well with Ditmar's figure." 



The carapace is gray-black, strongly marked with irregularly 



" Brit. Mus. Cat., p. 2.59. 



1- College Zoology, p. 530, fig. 440— from Zittel. 



" Reptile Book, p. 76, PI. 26. 



