THE PTJRBECK .BEDS AT SWANAGE. DORSET. 



377 



erected on the summit of the cliff ; and it was at this point (at 

 which Mr. Beckles, hoping to resume his labours, had purposely cast 

 down a large protecting accumulation of debris) that our attack 

 was finally made in the summer of last year, 1880. 



I must here render my tribute of thanks to my able coadjutor, 

 Mr. Henry Keeping, of Cambridge, for the skill with which he 

 directed the work, at no. little peril to those engaged in it. 



We commenced operations by scarping down the overhanging 

 strata for a depth of 40 feet, laying bare an area about 13 feet by 

 10. This upper "dirt-bed'" is of varying thickness, from 2 to 

 10 inches. It seems to have been a silt, filling up hollows and irre- 

 gularities in the surface of the stratum immediately below it. 



Aided by those earnest geologists Prof. Dawkins of Manchester, 

 Mr. Charles Potter of Liverpool, Mr. Griffith of Cambridge, and 

 several members of my own family, the area was most carefully 

 broken up and examined. The research occupied ten days ; and 

 although we found several teeth and jaws (hereafter to he described), 

 it was a fortuitous blow of the hammer of a local quarry-man that 

 laid bare the interesting specimen about to be described. 



The time of the meeting has already been trespassed upon too 

 long by these preliminary remarks. I hope on some future occa- 

 sion to supplement them by a further description of the fossils dis- 

 covered, a more ample account of the probable conditions under 

 which the deposits were formed, and the reasons which explain 

 the rarity of discovery rather than the paucity in number of the 

 Mammalian remains. 



With the jaw of Triconodon, and in the same bed, were found 

 Crocodilian remains (Theriosachus pusillus, Nannosuchus gracilidens, 

 and Nutlwtes destructor), with other Mammalian and Reptilian 

 fragments not easily determinable. There appears to be a single 

 tooth of Theriosuchus amongst the fragments, but whether of T. 

 pusillus is doubtful. 



It will be remembered that rather more than twenty years ago 

 extensive explorations were undertaken by Mr. Beckles, F.R.S., at 

 Swanage, in search of Mammalian remains, and that he succeeded 

 in unearthing some dozen new genera, including altogether sixteen 

 new species of Mesozoic mammals. These fossils consisted prin- 

 cipally of mandibles more or less broken, the only other bones 

 found being portions of the upper jaw. 



In the early summer of this year the permission of Lord Eldon 

 was obtained to renew the search in Durdleston Bay, Swanage ; and 

 although this search was not followed by such brilliant results as 

 in Mr. Beckles's case, it cannot be said to have been to no purpose, 

 since a very good Mammalian jaw was obtained. 



The specimen consists of the larger part of a right mandibular 

 ramus, of which the condyle, the upper border of the coronoid 

 process, and the symphysial end anterior to the second premolar 

 are wanting. Six teeth altogether are preserved in situ, and, with 



