42 Reports and Proceedings — 



The teetli include a pair of large round incisors, broken off close 

 to the sockets, and showing a large pulp-cavity, surrounded by 

 a complete ring of dentine, which is covered by a thin coat of 

 enamel on the front and sides. At 2 millim. behind each of these 

 teeth is the socket of a smaller premaxillary tooth; this tooth 

 apparently had a thin wall and a pulp-cavity relatively larger than 

 in the anterior tooth. It is separated by a ridged diastema from the 

 series of six molar teeth on each side, the first of which has a sub- 

 triangular crown with the base applied to the second tooth. The 

 latter and four following teeth are nearly similar, subquadrate in 

 form, with the crowns " impressed by a pair of antero-posterior 

 grooves, dividing the grinding-surface into three similarly disposed 

 ridges, and each ridge is subdivided by cross notches into tubercles. 

 Of these there are, in the second to the fourth molar inclusive, four 

 tubercles on the mid ridge, three on the inner ridge, and two on the 

 outer ridge." 



The author discussed the relations of this new form of mammal, 

 especially as indicated by the structure of the teeth, which he showed 

 to resemble those of Microlestes, from the Keuper of Wiirtemberg 

 and the Ehsetic of Somersetshire, and those of the Oolitic genus 

 Stereognathus, the former having on each tooth two multituberculate 

 ridges, and the latter three ridges, but with only two tubercles on 

 each. The fossil presents no characters to show definitely whether 

 the animal it represents was a placental or non-placental mammal. 



2. "Cranial and Vertebral Characters of the Crocodilian Genus 

 Plesiosuchus, Owen." By Prof. E. Owen, C.B., F.R.S., F.G.S. 



In this paper the author, with the view of showing that the 

 Kimmeridgian Sfeneosaurus Manselii, Hulke, really forms the type 

 of a distinct genus, discussed the characters by which Cuvier divided 

 the fossils referred by him to the Crocodiles into three principal 

 groups, to which Geoffroy St.-Hilaire gave generic names, and those 

 by which the latter author afterwards distinguished his genus 

 Sieneosauriis, including Oolitic forms, from the Liassic genus Teleo- 

 saurus. From his exposition of these characters the author con- 

 cluded that the above-named species does not belong to Steneomurus, 

 Geoff., and he proposed to make it the type of a new genus, Plesio- 

 suchus, characterized by the convergence of the frontal bones to a 

 point nearer the apex of the skull than in Steneosaurus, by the ex- 

 tension of the gradually attenuated nasal bones into a point pene- 

 trating the hind border of the nostril, and by other peculiarities of 

 the skull, teeth, and vertebrae. The author pointed out that this 

 form, like Steneosaurus, helped to bridge over the space between the 

 Liassic Teleosaurs and the Tertiary and recent Crocodiles, even ap- 

 l^roaching nearer to the latter than the older Oolitic tyjie. 



3. " On some Tracks of Terrestrial and Freshwater Animals." 

 By Prof. T. McKenny Hughes, M.A., F.E.S. 



The author's observations have been made on certain pits in the 

 district about Cambridge which are filled with the fine mud produced 

 in washing out the phosphatic nodules from the "Cambridge Gr^en- 

 sand " — a seam at the base of the Chalk Marl. As the water 



