0. P. Hay — Notes on species of Ichthyodectes. 229 



been published, a statement which certainly implies that figures 

 of it had not been published. 



I have in my possession portions of several individuals that 

 evidently belong to, or are very closely related to, Crook's 

 species, and I am convinced that if Prof. Cope's figures, desig- 

 nated as belonging to his Portheus arcuatus, really pertain to it 

 the latter and Ichthyodectes -polymicrodus are very different. 

 The parasphenoids of the two forms are different, as well 

 as other bones, as Dr. Crook has observed. The latter held 

 that Prof. Cope's figures belonged to Ichthyodectes anaides. 



Having settled this, we return to the description of the type 

 specimens of Portheus arcuatas, the maxillary and palatine. 

 I quote Prof. Cope's language : " Apart from its small size, 

 this species may be known by the compressed and concave 

 alveolar border behind and below the posterior maxillary con- 

 dyle and the very small size of the teeth which protrude from 

 it's subacute edge." It seems to me that this language and that 

 which follows it (Cret. Yert., p. 20±), as well as that employed 

 in Proc. Amer. Philos. Soc, xvii, 177, agrees so well with the 

 figure and description of Dr. Crook's species that no facts pre- 

 sented by him enable us to distinguish it from Prof. Cope's 

 species. Nevertheless, it seems hardly safe as yet to unite the 

 two. We ought to have more accurate descriptions of both. 

 In looking over my specimens it seems to me that lean observe 

 characters that indicate two species. In one maxilla I find 

 that the posterior, or palatine, condyle is comparatively short 

 and has in its hinder border a distinct notch ; in other maxillae 

 the condyle is longer and apparently without the posterior 

 notch. The distance between the condyles appears to be much 

 greater in some cases than in others. There also appear to be 

 some differences in the forms of the maxilla?. 



While these forms can by no means belong to Cope's Por- 

 theus (Xiphactinus of Leidy), they can hardly belong to the 

 genus Ichthyodectes. In the latter genus the maxilla is long, 

 nearly equal to the distance from the tip of the vomer to the 

 occipital condyle. The gape of the mouth must therefore have 

 been large. In Dr. Crook's species and related forms, the 

 maxilla is short, between one-half and two-thirds the distance 

 referred to above ; hence the gape of the mouth must have 

 been rather small. The maxillae of typical species of Ichthyo- 

 dectes are nearly straight along the tooth-line, or sinuous, or, in 

 I. hamatus, strongly concave. In I. i)olymicrodus the tooth- 

 line is strongly convex, except just behind the palatine condyle. 

 The teeth of I. 'polymicrodus are numerous and feeble : in the 

 other species strong and in smaller number. Hence, for Prof. 

 Cope's I. arcuatus and Dr. Crook's I. i?olymicrodus I propose 

 the new generic name 



