266 Mr. H. G. Seeley on Prof. Cope's Interpretation 



Fig. 12. Part of hind femur and tibia of Idotasia sca^yhioides, 

 Fiy. 13. Head of Osphilia apicalls. 

 Fig. 14. Right fore leg of Xychnsa larvata. 



Fig. 15. Front view of the head of Semiathe ophthalmica. The eyes are 

 scarcely large enough, and not sufficiently approximate. 



XXXIV. — Note on Prof. Co23e'8 Inferjyt'etation of the Ichthyo- 

 smirian Head. By Harry G. Seeley, F.G.S., Assistant 

 to Prof. Sedgwick in the Woodwardian Museum, University 

 of Cambridge. 



Professor Cope, in the ' American Naturalist ' for October 

 1870, published an illustrated absti-act of his recent memoir on 

 the crania of the lower Vertebrata. By the aid of these figures 

 many readers will become conversant with the curious new 

 interpretations which are among the results of Prof. Cope's 

 labours ; and this consideration leads me to offer the following 

 remarks upon the abstract of the memoir. As a briefer 

 notice has already been reprinted in the 'Annals' (1<S71, 

 vii. p. 67), it may be enough to state that from study of the 

 skull-bones which are immediately connected with the qua- 

 drate bone. Prof. Cope finds that previous writers have not 

 accurately determined the cranial elements in Ichthyosam'ia, 

 Dicynodontia, and others of the Monocondylia. And the 

 questions raised are questions of fact, concerning one or two 

 of which it is necessary to ask, Do the alleged facts exist '? 

 and if they exist, are they truly interpreted in the figures ? 

 On one point, that of the new interpretation of Ichthyosauria, 

 we have good materials in England for forming a judgment ; 

 and having had occasion in the last few years to study these 

 specimens in detail, I will endeavour to make Prof. Cope's 

 positions intelligible. 



First he finds at the back of the external nostril in Ichthyo- 

 saurus two small bones which are named the nasal bones. 

 There is no antecedent improbability in this determination; 

 the nasal bones commonly have such a position in all the 

 Vertebrata, and any deviation from such a plan may be re- 

 garded as exceptional. A consequence, however, of such an 

 identification is that a bone which Prof. Cope regards as the 

 principal frontal bone (nasal of authors) enters into the nostril 

 also; and against this there is a prima-facie probability, be- 

 cause the frontal bone has no such relation in vertebrates. 

 But the improbability is lessened when the nostril of Ichthyo- 

 saurus is seen to occupy the position usually held by the 

 middle hole of the skull (seen in Ornithosaurs, Dinosaurs, 

 Teleosaurs, &c.) ; and with that anteorbital perforation it may 



