DEVONIC FISHES OF THE NEW YORK FORMATIONS II3 



Asterosteus stenocephalus Newberry 



1875 Asterosteus stenocephalus J. S. Netvberry. O. Geol. Sur. Rep't, 

 Pal. V. 2, pt 2, p. 36, pi. 54, fig. I 



1889 Asterosteus stenocephalus J, S. Newberry. U. S. Geol. Sur. 

 Monogr. 16: 45, pi. 30, fig. i 



1891 Asterosteus stenocephalus A. S. Woodward. Cat. Foss. Fishes Brit. 

 Mus. pt 2, p. 312 



Only a few examples are known of this species, none of which display 

 the entire width of the head shield ; accordingly, previous descriptions 

 which represent the latter to be narrow and elongate are to be understood 

 as applying only to the median series of plates, between which sutures are 

 not distinctly traceable. The large, mesially placed openings between the 

 orbits are regarded by Woodward as nasal, an interpretation which we are 

 inclined to consider extremely doubtful in view of the invariable position 

 of the nasal openings in other Arthrodires, Sirenoids and Ctenodipterines. 

 The posterior flangelike projections on either side, called by Newberry 

 " condyloid prominences," correspond to the semicircular ridges just back 

 of the quadrate region on the inferior aspect of the skull in Macrope- 

 talichthys, and may have served for the attachment of the mandibular sus- 

 pensorium. Jaws and dental elements unknown. 



Formation and locality. Columbus and Delaware limestones ; Ohio. 

 Possibly also in the Onondaga limestone of New York. 



Family coccosteidaic 

 Cranial shield consisting of few elements, viz, a median and two external 

 occipital plates, in front of which is a single pair of large centrals more or 

 less in contact along the median line ; these are in turn preceded by a pair 

 of large preorbitals, which are either wholly or partially separated from 

 each other by the azygous pineal and rostral (" ethmoid ") elements ; pos- 

 terolateral border of the shield formed by the marginals and postorbitals. 

 Orbits not completely inclosed within the shield, bounded inferiorly by a 

 single suborbital plate, behind which occur one or two opercular elements. 

 Upper dentition consisting of a pair each of vomerine and palato-pterygoid 



