Kansas llNiyEiisiTY Science Bulletin. 



Vol. IV, No. 9. SEPTEMBER, 1908. 5^"^^^^^^^'^^ 



' ' / VOL. XIV. No Q 



Vol. XIV, No 9. 



ICHTHYOLOGICAL NOTES OF THE KANSAS 

 CRETACEOUS, I. 



BY C. E. McCLUNG. 

 (Contribution from the Zoological Laboratory, No. 176.) 

 Plates X to XIII, and ten figures. 



DURING the course of a restoration of the extinct Creta- 

 ceous fish, Xiphactinus Leidy, a number of points con- 

 concsrning its anatomy came up for consideration. Sev- 

 eral of these called for considerable study, and it was found that 

 they had not been completely worked out before in any specimen. 

 In particular, these concerned the pectoral girdle, the opercular 

 apparatus, and the mandible. It is my purpose in this paper 

 to present, among other things, the facts that appeared from 

 this study. 



OPERCULAR BONES OF XIPHACTINUS. 



Of this series the operculum, preoperculum, and subopercu- 

 lum have received extended descriptions at the hands of Stew- 

 art, but the exact identity of the suboperculum was not deter- 

 mined, since it is indicated as the "supposed suboperculum." 

 The interoperculum is figured under the caption of "bones of 

 uncertain position." While this entire series has not been ob- 

 served in position, I feel confident that the relations indicated 

 in figure 1 cannot be far wrong. From the inner side it can be 

 seen that the interoperculum upon this surface has a facet that 

 articulates with a corresponding one on the suboperculum, and 

 when these are in contact and the bones in position the oppo- 

 site, roughened extremity of the interoperculum just comes 

 into contact with the rugose angular of the mandible. I am 

 therefore of the opinion that the location of the members of 

 this series has been determined with some degree of certainty. 

 Unfortunately the interoperculum is very thin and fragile on 



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