Ch. XX.] IX MIDDLE PURBECK. 3S5 



Owen has likened them, he will, I think, he as much at a loss as Dr. 

 Falconer to recognize any resemblance between them. 



All the fossil bones of mammalia discovered before the year 1857, 

 in rocks older than the tertiary, had consisted exclusively of single 

 branches of lower jaws, and it is a singular fact that Mr. Beckles 

 should have sent to London in that year the first known example of 

 the upper portion of the skull of a secondary mammal consisting, as 

 Dr. Falconer pointed out to me at the time, of the two frontal and the 

 two parietal bones in a good state of preservation, with the sagittal 

 crest well marked, and the occipital also with its crest. Although the 

 lateral and basal portions of this cranium were wanting, enough re- 

 mained to show that it agreed with the ordinary type of living warm- 

 blooded quadrupeds. 



In the same slab with this cranium occurred the entire side of the 

 lower jaw of another quadruped, to which Professor Owen gave the 

 generic name of Triconodon. It contains eight molars, a large and 

 prominent canine, and one broad and thick incisior. This creature 

 must have been nearly as large as the common hedgehog. 



Several other jaws with similar tricuspid teeth of larger dimensions, 

 found by Mr. Beckles, indicate the existence of another species of 

 Triconodon of a more elongated form, and about one-third larger in 

 size. Its marsupial character was inferred by Dr. Falconer from the 

 number of the true molars, the strong inflected angular process, the 

 broad salient everted rim of the ridge which is decurrent on the outer 

 side from the condyle along the inferior margin, and the marked 

 development of the milo-hyoid groove. He also observed that these 

 two species of Triconodon were more like small ferine animals than 

 mere insectivorous marsupials, and that they probably fed on prey less 

 minute than insects. This opinion he deduced from the cutting char- 

 acter of then* teeth, and their comparatively formidable canines, 

 together with the form of the ascending ramus. 



Professor Owen has proposed the name of Galestes for the largest 

 of the mammalia discovered in 1858 in Purbeck, equalling the pole- 

 cat {Mustela putorius) in size. It is supposed to have been predaceous 

 and marsupial. Its generic character is derived from a peculiar modi- 

 fication in the form of one of the pre-molars, which has a single exter- 

 nal vertical groove. 



When Mr. Beckles had found the remains of twenty-eight distinct 

 individuals of Purbeck mammalia, and Mr. Brodie seven other speci- 

 mens, they all consisted of lower jaws, and only five of them had upper 

 jaws in connection ; and the ten other specimens of oolitic mammalia 

 belonging to four species discovered at Stonesfield were in like manner 

 all represented by lower jaws. That between forty or fifty species or 

 sides of lower jaws with teeth should have been found in oolitic strata, 

 and with them only five upper maxillaries, together with one portion of a 

 separate cranium, will naturally excite surprise. There were no ex- 

 amples in Purbeck of an entire skeleton, nor of any considerable num- 

 25 



