126 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 17, 



be marked : in travelling along the Great Western line of railway, 

 a section may be observed in deep cutting a little to the north of 

 Swindon. Indeed, the Coral-rag may be occasionally observed 

 capping the minor hills in advance of the long chain of the Wilt- 

 shire chalk-range. Occasionally, though our sections and those 

 of Lonsdale and Fitton would make it appear that the Coral-rag 

 is a continuous stratum, having the Oxford Clay below and the 

 Kimmeridge Clay above, it seems in North Wilts to occupy only 

 hummocks, and to be sometimes wanting altogether, when the line 

 of demarcation between the two clays just named is exceedingly 

 difficult to determine. The district now under review, however, is 

 not the best in which to study this bed, as it is here only par- 

 tially developed, and its accompanying drifts of the Calne district 

 are entirely absent : in the words of Lonsdale, " The rubbly oolite 

 constitutes the greater part of the Coral-rag of Wiltshire ; it is 

 formed of a nodular limestone of an earthy aspect, a brownish, 

 yellowish, or blueish white colour, and abounds with fragments of 

 echini and shells*." This very well describes the rock of my 

 section. 



Thin as the stratum is in this district, it is very rich in fossils, 

 and amongst others found at Blunsdon are the following 



Corals. 

 Thecosmilia annularis ^ 



^^Ddabech" See Mo ™S ra P h b y Edwards and 



Thamnast'rL'arachnoides ( Haime (Palaeontographical Society). 

 Isastraea explanata _, 



Echinoderms.f 



Cidaris Blumenbachii, Munster. Diaderaa subangulare, Goldfuss. 



Diadema depressura, Agassiz. Nucleolites dimidiatus, Phill.% 



Bivalve Shells. 

 Modiola inclusa§, ] 



Pecten insequicostata, > Phillips. 

 Crassina ovata, J 



Univalves. 

 Turbo muricatus, Geol. York., pi, iv. f. 14. 



funiculatus, id. pi. iv. f. 11. 



Turritella muricata, id. pi. iv. f. 8. 



Ammonites. 

 Ammonites perarmatus||, M. C. t. 352. Ammonites triplex, M. C. t. 292. 



It is worthy of note that the Brachiopoda seem not to be represented 

 in the Coral-rag. 



* Lonsdale on tbe Oolite District of Bath, Geological Society Transactions, 

 2nd ser. vol. iii. p. 241, &c. Read 6th Feb., 1829. 



f The species are so common as to be found in handfuls ; the test, however, 

 is difficult to obtain perfect. 



X Sometimes occurring in masses. 



§ Abundant in galleries in the corals. 



II This and the following are frequently of great size. 



