Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/500

 tain seven, also circular, teeth in each ; the teeth of the marginal row are slightly truncated on the outer edge. This specimen was also found in the Kimmeridge Clay at Kimmeridge, and must probably be referred to the species named by Agassiz Sphoerodus gigas.

2. Note on a large Saurian Humerus from the Kimmeridge Clay of the Dorset Coast. By J. W. Hulke, Esq., F.R.S., F.G.S.

[Plate XVI.]

For the opportunity of bringing before the Society this remarkable bone I am indebted to the great courtesy of J. C. Mansel, Esq., who, in reply to an inquiry addressed by me to him respecting the genus Pliosaurus, most liberally transmitted to me for study a large number of specimens from his unrivalled collection of Saurian bones from Kimmeridge, amongst which was the subject of this note. Mr. Mansel writes to me that this bone was found last year " amongst the layers of shale immediately above the band of cement-stone which rises from E. to W. on the west side of Clavell's Tower, between Kimmeridge Bay and Clavell's Head ; " and he called my attention to it as differing from the common Enaliosaurian limb-bones.

Description, — This stupendous bone has transversely elongated extremities and a subcylindrical shaft. It has been broken across at about 7 inches from its proximal extremity, and again 1 foot from its distal end. Owing to the loss of small portions by splintering and abrasion, the surfaces of the distal fracture do not meet accurately. A long slip, reaching from this fracture to the anterior* angle of the proximal terminal surface and including a small piece of this latter, has been broken off the anterior (outer) border of the bone and is wanting, as are also both the terminal epiphyses†. The terminal surfaces are mammillated and rugous, and scarcely at all abraded. The surface of the shaft is smooth and polished, composed of a very dense cortex which in this situation is about .5 inch thick, but which grows thinner towards the extremities, where also its texture is less compact and its surface is rougher and coarsely striated. There is no medullary canal. All the fractured surfaces distinctly show the interior to consist of cancellous tissue.

Proximal extremity. — This is much flatter than the distal. The transversely lengthened convex terminal surface measures 11 inches along the curve. Originally its length was somewhat greater ; for a small piece of its front (outer) end is wanting. Its posterior end,

the borders and surfaces when the axis of the bone is supposed to lie in a nearly horizontal plane, and nearly perpendicular to the axis of the trunk.
 * The terms anterior, posterior, upper, and under indicate the directions of

† The term " epiphysis " is used here in a modified sense. "Dans les crocodiles et les tortues, les extremities des os et leurs principales eminences sont enduites de cartilages plus ou moins epais, qui durcissent et s'ossifient avec l'age, mais dans lesquels il ne se forme point, comme dans les mammiferes, de noyau osseux, separe pendant quelque temps du corps de l'os ou dela diaphyse par une suture ; circonstance d'autant plus singuliere, que les sauriens, specialement les monitors, ont a leurs os longs des epiphyses tres-marquees." — Cuvier, Ossemens de Reptiles, 1824, viii. p. 8.