232 0. P. Hay — Notes on species of Ichthyodectes. 



others. The hyomandibular seems to have had on its inner 

 face a deep excavation, somewhat like that which J have de- 

 scribed in the case of Xiphactinus (Zoolog. Bulletin, vol. i). 

 I have not enough of the vertebral column well preserved to 

 enable me to determine its characters in this genus. It was 

 doubtless much like the vertebral axis of Ichthyodectes and 

 Xiphactinus; most of the vertebra possess one or two deep 

 grooves in each lateral surface. The upper arches were not 

 coossified with the bodies of their vertebrae. Their bases 

 occupied nearly the whole length of their centra ; and evi- 

 dently they came into contact in front and behind with the 

 preceding and the succeeding arches. That there were any- 

 where in the vertebral column accessory pieces entering into 

 the construction of the upper arches, such as I have described 

 in Xiphactinus, I cannot affirm, but their presence seems 

 probable. 



On a block of soft limestone in my possession there occur a 

 maxilla, a preopercle and several scales of an individual of 

 this genus. The palatine condyle of the maxilla is relatively 



short, has a notch in its posterior 

 end, and is separated from the an- 

 terior condyle by a space equal to 

 two-thirds the length of the palatine 

 condyle. A drawing of the pre- 

 opercle, two-thirds the natural size, 

 is here presented (fig. 5). The scales 

 were relatively very large. Judg- 

 ing from the size of the maxilla, the 

 fish could not have exceeded 60 cm 

 (2 feet) in length. Nevertheless, 

 one of the scales has a height of 

 44 mm . The imbedded portion of the 

 scale is marked by grooves which 

 radiate from the center of the scale 

 and which are separated by spaces 

 wider than themselves. The ex- 

 posed portion of the scale appears 

 to have been covered with numerous sharp points, which must 

 have given a roughness to the whole body. These points were 

 largest just behind the center of the scale. Toward the hinder 

 edge they became smaller, and here the scale became striated 

 with narrow grooves and ridges. It seems not unlikely that 

 the free edge of the scale was pectinated, as in Brevoortia. 



U. S. National Museum, Washington, D. C. 



