42 



Dr. O. P. Hay has informed the writer that in the type specimen there is little, if 

 any, of the carapace represented, that the anterior lobe of the plastron is missing, and 

 that the specimen shows the central portions of the plastron, and the posterior lobe, which 

 latter is broadly rounded. 



Belly Eiver series, Eed Deer river, 1 89*7, 1898 and 1901. 



Fragments of the shell had been collected as follows : — Professor John Macoun, 

 Mackay creek, 1880 (Belly Eiver series) ; Dr. Gr. M. Dawson, on Old Man river, below 

 Fort McLeod, 1881 (Willow creek subdivision of the Laramie) ; Mr. E. G-. McOonnell, 

 Eed Deer river, 1882 (Belly Eiver series). 



CHELYDEID^. 



Netjrankti.us. G-en. nov. 



Neurankylus EXiMius. Sp. nov. 



The carapace of a turtle, repre- 

 sented by costal and other bones, 

 shown in fig. *7, is remarkable for 

 certain peculiarities of structure. 



Of the seven costal bones ob- 

 tained, from the middle and poste- 

 rior parts of the carapace, four were 

 found as shown, united to a large 

 neural and a suprapygal bone. The 

 other three costals, viz., the third 

 pair and the right fourth were with 

 the posterior costals but not in 

 place. The fifth pair of costals was 

 missing. The sulci indicating the 

 junction of the costal shields seem 

 to be normal in their position on the 

 4th, 6th and 8th costal bones. What 

 is apparently a 9th costal succeeds 

 the 8th costal bone. The 1th, 8th 

 and 9th pairs of costals do not reach 

 the median line of the carapace, but 

 are separated by a large bone that is probably formed by a coalescence of the 8th neural 

 with a suj)rapygal. This enlarged 8th neural is suturally united, for some distance 

 with the vertebral ends of the Tth costal bones, for the whole of their breadth to the 

 8th costals and to a considerable portion of the supposed 9th costals. It increases in 

 breadth posteriorly and effects a sutural union with a suprapygal whose breadth 

 greatly exceeds its length. The rib-heads of the costals are well formed, those of the 9th 

 costals being as fully developed as the others. No marginal bones were found with the 

 remains of the carapace. Anterior to the point " a " on the outer edge of the 9th 

 costal, vacuities seem to have occurred between the costals and the marginals, judging 

 from the appearance of the outer margins of the 8th and 9th costals. From the point " a " 



Fig. 7. — Part ol inc oary-puct of j.\'taranh/tu-i eximius, one-third the 

 natural size. N. 3, //, &c., neural bones;, C. 3, 4> £&«■, costal 

 bones; .s^jy, suprapyg-al bone ; r, rib-end. The heavy lines indicate 

 tlie boundaries of the epidermal shields, the sinuous ones the sutures 

 between the bones, and the dotted ones the parts restored. 



