BRITISH FOSSILS. 



5 



Burton Bradstock, and near Burton Castle (top beds), Bridport Har- 

 bour, Chideock Hill, Mapperton, West Swillets, Beaminster. These 

 localities are all included in sheets 18 and 19 of the Ordnance Map of 

 England. The specimens were collected by Mr. Bristow and Mr. 

 Gapper. 



Foreign Distribution. — " In Normandy, in a particular bed of the 

 Calcaire au Polypiers, known by the name of Caillasse." (Desor.) *' In 

 the Inferior Oolite of the Tour-du-Pre associated with Dysaster ringens 

 and Diadema depressum^ (Cotteau.) 



EXPLA.NATION OF THE PlATE, 



Fig. 1. Normal form seen from above. 

 Fig. 2. Under view. 

 Fig. 3. End view, showing the anus. 

 Fig. 4. Profile. 



Fig. 12. Extremely depressed specimen (var. jS), seen endways. 



Figs. 13 and 14. Outlines of end, over and under side of extremity, conical dwarf 

 variety (var. y). 



Fig. 5. Arrangement of ambulacral and interambulacral plates and pores on the sides. 

 Fig. 6. Ditto on the base. 



Fig. 7. Mode of duplication of the notches of the mouth-margins ; and arrangement 

 of the oral terminations of the avenues. 



Fig. 8. Apical disk, showing the arrangement of the genital and ocular plates, and 

 the madreporiform tubercle. 



Fig. 10. Tubercle and granules of dorsal surface highly magnified. 



Fig. 11. The same from the ventral surface. 



Note on allied species of Galerites found in Britain, 



The only British Galerites of the section Holecttjpus, besides the one described above, 

 is the G. depressa, a species which accompanies G. hemisphcerica in most of the localities 

 cited, and which has a much wider distribution, occurring, in England, in inferior oolite, 

 where it appears to be most abundant, in fullers' earth and in cornbrash. It is at once 

 distinguished from G. hemisphcericahj the position of the anus, which is entirely ventral, 

 very large, extending from very near the mouth to the margin of the under surface, and 

 of an oblong pyriform shape, pointed at its inner end,'^and widest towards its marginal 

 termination a little beyond half its length. The dorsal surface is depressed, yet regularly 

 convex, the margins rounded, but having a tendency to compression, consequently the 

 greatest breadth of the entire body is in the diameter immediately above the margin. The 

 spiniferous tubercles of the dorsal surface are very small ; they are very numerous near 

 the edge, but become fewer and more scattered, though very conspicuous and compara- 

 tively large, on the ventral surface, as they approach the mouth. Individuals vary greatly 

 in the degree of dorsal convexity. From one inch to one inch and a-half across is the 

 usual diameter of well-grown specimens. 



Edward Forbes. 



June, 1850. 



