244 KANSAS UNIVERSITY SCIENCE BULLETIN. 



fin-rays and baseosts are similar in form and position. The 

 two cup-shaped depressions for the reception of the T-shaped 

 baseosts are present and the first is bisected by the suture sep- 

 arating the hypercoracoid from the intercoracoid. The meso- 

 coracoid, like all the other bones of the girdle, is not so robust 

 as the corresponding element of Xiphactinus, but in form and 

 position is similar to that of the larger fish. Indeed, the very 

 evident and minute resemblances between the pectoral fin appa- 

 ratus of Gillicus and Xiphactinus clearly point to the close re- 

 lationship between the genera and justifies their inclusion in a 

 common group. 



GIRDLE OF PROTOSPHYR^NA. 



The girdle of this genus has been described at considerable 

 length by Cope and Hay, and the specimens at my command 

 enable me to add only some small details to what has already 

 been published. In figure 9 is shown an external view of the 

 clavicle, from which it is evident that only a part of the bone 

 has previously been figured. Hay shows in his figure 7, page 

 13, the most complete specimen that I have seen mentioned. 

 Cope represents only fragments attached to the heavier bones. 

 On the dorsal limb the cephalic edge is much thickened (figure 

 10), strengthening the girdle after the manner of the meso- 

 coracoid in Xipthactinus. The specimen from which figure 9 

 was made is not well preserved, having been taken from the 

 shaly lower stratum of the chalk, but the outline of the entire 

 bone was preserved in the matrix and is shown in the restora- 

 tion. 



The relations of the complex of girdle bones is shown in 

 figure 10, drawn from a specimen that has suffered very little 

 distortion. Unfortunately, the sutures are almost entirely 

 obliterated by the close union of the various bones, so that 

 little can be added to what is already known regarding the 

 limits of the individual elements. Owing to the undistorted 

 condition of the specimen, however, the exact form and position 

 of the various parts are clearly shown. Thus the mesocoracoid 

 is observed to occupy somewhat the same position that it does 

 in Xiphactinus, leaving an oval foramen between itself and the 

 upward extension of the hypercoracoid. Instead of being su- 

 turally connected with the clavicle it rests in a depression 

 formed by the straight, ventral extension — past the curved 

 cephalic edge — of the thickened process of the clavicle. The 

 hypercoracoid is not suturally separated from the hypercora- 



