38 



broadest at the sides of the carapace aud narrowest in front, extends along the whole of 

 the peripheral edge. 



As regards a divided first neural in species of this genus, it is interesting to note 

 that Lydekker, in describing T. melttensis, from the Miocene of Malta, in 1891 ^Quarterly- 

 Journal of the G-eological Society, voL xlvii, p. 37, iig. 1), mentions the occurrence in the 

 Miocene species of a divided first neural, and remarks (p. 37) that " all the fossil species 

 hitherto described, of which the entire carapace is known, agree with the normal type in 

 having but a single long neural between the first pair of costals." 



Measurements. 



M. 



Length of carapace along median line (18^ inches) • 470 



Maximum breadth of carapace {'^'^^ inches) • 590 



Breadth of first costal at inner end '075 



Thickness of same near inner end • 009 



Thickness of same at outer end , '012 



Breadth of fifth costal at outer end "119 



Thickness of same at outer end "013 



Breadth at mid-length of seventh costal -036 



Thickness at centre of eighth costal '010 



Maximum breadth of neural 1 ■ 056 



Maximum breadth of neural la • 039 



Length of same ■ 043 



Thickness of nuchal plate at left end '018 



Length of vertebral centrum • 045 



Belly River series, Eed Deer River, 1897, 1898 and 1901 ; besides the carapace above 

 described, separate costals and neurals, and parts of the endoskeleton. 



Also in 1880, Professor John Macoun, neurals and fragments of coatals, from Mackay 

 creek, near Walsh, a station on the C. P. R., about twenty-eight miles east of Medicine 

 Hat; aud in 1881, Dr. G-. M. Duwsou, from Belly river, N. W.T. (No. 41), fragments of 

 costal bones. 



ADOCID^E. 



Adocus, Cope. 



ADOCUS (?) LINEOLATUS, Cope, 



Adocus (?) lineolaltis, Cope. 1875. Report U. S. Geol. Survey Terrs., vol. ii. Vertebrata of 

 Cretaceous Formations of the West, p. 92, pi. vi, figs. 11 and 12. 



This species, readily recognized by its neat aud characteristic sculpture, is repre- 

 sented by two well i^reserved fragments, one, part of the right hyoplastral, the other, from 

 the margin of the carapace in advance of the right axillary notch. The sculpture has the 

 appearance of that of Adocus vuriolosus, in miniature, with the roughness worn down. 



Belly River series, Red Deer river, 1901. 



