30 



parallel or divergent ribs that, in places, frequently coalesce and are sometimes inter- 

 rupted ; when divergent, additional ribs are intercalated at intervals. Fragments of 

 spines with parallel grooves and ridges, running in the direction of the length, are 

 thought to belong to the same fish. 



^o^ 



These remains resemble, somewhat, the corresponding parts of some of the species of 

 Rhineastes described by Cope from the Tertiary of the v/estern States, and are here 

 assigned, at least provisionally, to that genus. 



Belly River series, E.ed Deer river, 1901. 



DiPHYODUS. G-en. nov. 



DiPHyODUS LONGIROSTRIS. Sp. UOV. 



Plate 5Y., figs. 18 and 19. 



The bone figured on the above plate affords evidence of the complete coalescence of 

 the premaxillaj in a fish to form a long, slender, snout armed with teeth that succeeded 

 each other in a regular alternating manner. These characters have suggested the names 

 of the genus and species proposed. 



The specimen is in the form of a comparatively thick plate bent, on itself, so as to be 

 U-shaped in transverse section ; it is imperfect at both ends, is 23 mm. long, tapers slightly 

 toward the from, and is 4 mm. broad posteriorly and 3'5 mm. broad at its anterior end. 

 There is no evidence of a median longitudinal suture. The sides of the hollow semi-cylin- 

 der thus formed, are slightly over 1 mm. thick, but the thickness of the basal part is over 

 2 mm. On the flattened upper surface of the two sides, are preserved, circular bases of 

 teeth, anchylosed to the bone, that appear as raised circles, averaging '80 mm. in diameter 

 and aboixt 2 mm. apart from centre to centre. On the right side there are nine teeth repre- 

 sented at equal intervals, but on the left side, although there were a like number of 

 teeth, the interspaces are not so regular. Shallow subquadrangular depressions, varying 

 in number from one to three, according to the length of the interspace, occur between 

 the tooth-bases. Each depression represents the former position of a tooth that has fallen 

 out or has been broken off. 



A circle of minute pits or foramina surrounds each tooth-base ; similar but less 

 regular pits occur in the intervening depresssions and a few are observed within the 

 tooth-bases themseh'es. Two tubular canals, placed side by side, above the centre of the 

 base, pierce the bone longitudinally throughout its length. The bottom of the median 

 groove between the two rows of teeth has an undulating surface. The sides and rounded 

 base of the bone are smooth and show irregular longitudinal lines of small pit-like 

 markings. One of the tooth-bases at the posterior end is decidedly subquadrangular or 

 oval in shape with its larger diameter transverse. 



Two or three fragments present the same characteristics of structure. 



Belly River series, Red Deer rive:, 1901. 



