SG 



Tirro BONE-CAVE OK PISSUEI! OF UOEWIAM DOWN. 



cavities. Thoro arc two models * in tlic Museum, each of 

 which delineates a fissure. The fissures thus delineated, 

 however, whilst not absolute counterparts, have the same 

 general character, consisting of a narrow, nearly voi'tical, 

 cleft, opening at the surface of tlio ground, widening out 

 and divided below by sharp roclcy pi'ojections, and con- 

 tinuing downwards into a more spacious horizontal chamber, 

 whence a narrow pipe-like fissure proceeds vertically down- 

 wards (see Plates III. and IV.). t So nearly do the two 

 models agree, both in their genei'al and detailed conformation, 

 that I look upon them as right and left-hand illustrations at 

 two contiguous points of one and the same fissure, which 

 had been cut thi'ough and exposed by quai'iying opeiutions 

 carried forwards in a transverse dii'ection. One of the models 

 is constructed in two halves, in order to show the continuation 

 of the large lateral cavity, and the parallel pei'pondicular 

 fissure, also opening out of the surface, as described by Mr. 

 Stutohbury. 1 infer then that the Durdham Down " Bono 

 Cave " consisted essentially of a single line of fissure running 

 roughly cast and west; that this fissure was, generally speak- 

 ing, a narrow cleft, but that it luid here and there boconio 

 widened out laterally, so as to show at least two surface 

 openings of appreciable size; that similar expansions of the 

 fissure occurred at a depth from the surface, which wei-o in 



* Tfiese modofs wero fately unoarthod in the attics of the Institution, 

 and have now been roHtorod and placed in tfic Museum. I had pre- 

 viously noticed a smaller set of models of the same fissures in a museum 

 cabinet ; and I may say that my only moans of identifying these models 

 with the Durdham Down fissures is a ponoil-note to that effect in an old 

 catalogue of museum duplicates, taken in connection with the descrip- 

 tion in Mr. Stutchbury's report. 



t On one of the models there arc figures to show that the de|illn (from 

 the surface) to the top of the hole {i.e., the pipe-like fissure) was SG feet, 

 and from this point to tho bottom of tho hole 37 feet. 



