418 MR. J. W. HULKE ON THE SKELETAL [NoV. 20, 



the Oxford Clay *, near Peterborough, obtained by A. Leeds, Esq., 

 to whom I tender my warm thanks for most courteously affording 

 me an opportunity of studying them at leisure during the past 

 winter. They are easily freed from the clay by washing, after 

 which many of the bones, except for some crushing by earth-pressure, 

 are nearly as complete as freshly macerated osteological specimens. 

 The mode of their occurrence in the rock, their fades, and their 

 relative proportions concur in affording a high degree of probability 

 to Mr. A. Leeds's conviction that each of his series represents one 

 individual, and is not derived from several skeletons. An im- 

 pression that they help to clear up some points in the skeletal 

 structure of the earlier Crocodilians hitherto obscure and requiring 

 confirmation is my apology for offering an account of these remains. 

 Mr. Leeds's collectiou contains remains referable to both the 

 primary groups into which Messrs. E. and E. E. Deslongchamps in 

 their classical ' Memoirs ' (6) divide the family Teleosauria ; their 

 genus Teleosaurus is exerapHfied by a member of the subgenus 

 Steneosaurus, and their genus Metriorhynchus by probably more 

 than one species. Mr. Leeds tells me that Steneosaurian remains 

 occur sparingly and they are restricted to the upper beds, whereas 

 those of Metriorhynchus are plentiful, and they are distributed 

 throughout the whole series of the beds, from the uppermost to the 

 lowest exposed in the pits. 



The cranial characters distinctive of the two genera laid down by 

 Messrs. Deslongchamps (7) are plainly recognizable in the skulls in 

 Mr. Leeds's collection. As, however, these are much crushed and 

 otherwise imperfect, I do not offer any description of them. 



Meteiorhynchus. 



VertebrcB. — All, except the first two and the two sacral, have both 

 terminal surfaces of the centrum more or less concave, the character 

 which stamps the Profosuchii of E.. Owen (8), the Mesosuchia of 

 T. Huxley (9), and distinguishes these from all the more recent 

 Crocodilians, including those of Tertiary age and also the extant 

 members which together compose Huxley's suborder Eusuchia (10). 



Atlas. — This vertebra (Plate XVIIL fig. 1) is composed of the 

 same elements as in extant Crocodiles, viz. — of an azygos ventral 

 piece ("basilar Stiick," Stannius) (11); of a pair of lateral pieces 

 which, in conjunction with the basilar piece, constitute an incomplete 

 ring ; of a pars odontoidea ; and of an upper piece (" piece supe- 

 rieure," Cuvier ; oberes Schlussstiick of German zootomists). The 

 existence of this last element may not be doubted, although it is not 

 preserved in any atlas in the collection, since its presence has been 

 demonstrated in the earlier Crocodilians of the Lias (12), in those 

 of contemporary rocks in Normandy (13), in those of Tertiary 

 rocks (notwithstanding Ludwig's opinion that it is absent from the 

 Crocodilians of the Mayence basin (14) — an idea founded on a mis- 

 apprehension), as it is also in all extant Crocodilians. 



^ Through misapprehension of information given me respecting these pits. I 

 was formerly under the impression that they were in the Kimmeridge Clay. 



