August 19, 1870. '*'^' [Cope. 



Prof. Cope stated that he had been acquainted for some time with a 

 Mososauroid reptile from the white rotten limestone of Alabama, and had 

 formerly thought it to be the Mososaurus brumbyi, of Gibbes. He was 

 satisfied of the error of this determination, and as the hasmal arches of the 

 caudal vertebrse were not co-ossified, he referred it to the genus Liodon, 

 under the name of L. perlahos. A dorsal vertebra had been already de- 

 scribed in the Synopsis of Extinct Batrachia and Reptilia of North 

 America, Trans. Amer. Philos. Soc, 1869, 198. 



Prof. Cope communicated some results of his studies of the structure of 

 the crania of the orders of Reptilia and Batrachia, recent and extinct. 

 He exijlained the characters of the Ichthyopterygia as follows : 



The quadratojugal present (squamosal of Owen, Anatomy of the Ver- 

 tebrata); postorMtal (of Owen) present.. The sqttamosal (supratemporal 

 of Owen) extending over the inner side of the parieto-squamosal arch so 

 as to conceal the parietal portion of it, to the anterior part of the tem- 

 poral fossa, and in contact with its fellow of the other side. It sends 

 down a columella to the pterygoid. It extends also for a remarkable 

 distance downwards behind the osquadratum. '^ Opisthotic present. A dis- 

 tinct element exists behind the quad ratum, which he thought might be the 

 suprastapedial, otherwise called the incus, or hyomandihular, according 

 to Huxley. The pterygoid prolonged backwards and expanded, in contact 

 with the basi-occipital, and extending from it to the quadratum. The pos- 

 terior pair of elements of the superior face of the cranium being deter- 

 mined to be squamosals, the interpretation of the anterior elements be- 

 comes simple. The rhombic element with fontanelle is parietal (frontal 

 of Owen Anatomy of Vertebrata), and the preceding pair are tlie frontals 

 (nasals, Owen). The true nasals were shown to lie at the proximal end 

 of the nares. 



The structure of the suspensorial region in the Auomodont, Lystro- 

 saurus, was next pointed out. In this order there is no quadratojugal 

 arch, and the zygomatic arch contains a very small postorbital. The 

 squamosal has an extraordinary development, and extends on tlie parieto- 

 quadrate arch, and on the inner side of the temporal fossa on each side of 

 the parietal. The parietal is not so far concealed as in Ichthysaurus, but 

 its posterior-lateral process may be seen wedged in between the squamosal 

 and the thin, plate-like opisthotic, which lies external to the supraoccipi- 

 tal on each side. The opisthotic is the parietal of Owen, and the parietal 

 branch of the squamosal is the mastoid of the same author. 



This branch in Ichthyosaurus and Lystrosaurus is continuous with the 

 zygomatic portion of the bone, though another element might have been 

 originally coossified with it. The posterior portion of the squamosal is 

 prolonged remarkably, it is applied to the posterior face of the quad- 

 ratum, and extends to its articular extremity. The quadratum is, a small 

 bone of a plate-like form, in contact with the squamosal above and the 

 ? prootic inwardly and anteriorly. Su^jrastapedial wot Aistmguish&d.. The 

 parietal branch of the squamosal sends down a columella to the pterygoid. 



A. p. s. — VOL. XI — 35e 



