Page:Quarterly Journal of the Geological Society of London, vol. 35.djvu/199

Rh the eggs and newly hatched brood, of the cold-blooded amphibious giant.

When, therefore, my cogitations had been turned to any possible relations of a Phascolothere or a Triconodon to the amphicœlian Crocodilia of the Oolitic or Wealden periods, I thought of the diminutive contemporaneous mammals as reducers of the numbers of such Crocodiles, assuming that the reptiles may have sought the banks or shores to oviposit, and that their eggs and wriggling brood may have tempted the small predatory marsupials, as those of the procœlian Crocodiles do their contemporaneous species of Herpestes.

Pursuing, however, my researches on the Crocodilia of the Purbeck series, I have come, as I believe, upon a relation of them to their contemporary diminutive mammals at once most interesting and unsuspected. The Spalacotheres, Peralestes, Stylodons, Triconodons, &c. of the freshwater deposits of the "Feather-bed" may well have been the prey of the Crocodiles of the period; for these Crocodiles were reduced to dimensions which forbade them to disdain such succulent morsels, and, at the same time, they were suitably armed and limbed for the capture of the little marsupials.

The characters of one of these dwarf Crocodiles I now propose briefly to submit to the Geological Society; fuller details and illustrations of this and other small crocodilian genera and species will appear in the forthcoming volume of the Palæontographical Society.

The subjects of the annexed Plate (Pl. IX.), all of the natural size, are selected from numerous evidences of the species, which I propose to name Theriosuchus pusillus.

These and other Crocodilian evidences of the Purbeck period have been brought to light, or completely exposed, by operations upon the residuary slabs of "Feather-bed" marl which accompanied the Becklesian collection to the British Museum, when the negotiations for the purchase of the whole were concluded.

They are very numerous, chiefly consisting of scattered teeth, scutes, vertebræ, and detached limb-bones, but likewise of a few skulls and mandibles, and, in one or two instances, of considerable portions of naturally connected skeletons. The scattered parts associated with these have served for the ascription to their several species of answerable bones, teeth, and scutes not so associated.

At the first aspect, detecting in the scattered groups of scutes specimens showing the peg (Pl. IX. fig. 10, a) and groove (fig. 11, b), it seemed as if remains of some young specimens of Goniopholis had been brought to light. The condition, however, of two of the skulls, one of which has yielded the subjects of figs. 1, 2, 3, Pl. IX., enabled a comparison to be made which determined their specific and, by