rm ] 273 



greensand, and how inany of the species plentiful upon it in the 

 southern counties attain its most northern limit in Yorkshire. Then 

 a further series of enquiries suggests itself as to how far these species 

 follow the chemically allied, though far removed, and much hardened, 

 carboniferous, and other limestones which lie in strips and spots in 

 Devon, all along the "southern portions of South Wales, and even 

 in the extreme north of the Principality ; also in larger extents 

 in Derbyshire, Lancashire, East Yorkshire, Westmoreland, Cumber- 

 land, and Northumberland. That some of them do extend their range 

 on to portions of this formation is certain, since I have found 

 Polt/ommatus AJsus and Melanippe rivata not scarce in South Pem- 

 brokeshire, where also Euholia bipunctaria was very common, and the 

 beautiful little Eanychia cingpXalis inhabited sheltered slopes of the 

 limestone cliifs. 



Devon is a county of contrasts. Its large middle area is millstone 

 grit, this is edged on the north and south by a broad strip each of 

 carboniferous limestone ; north of this is red conglomerate of lime- 

 stone and sandstone (Exmoor district) ; south of the southern strip 

 of limestone the great granite mass of Dartmoor ; eastward, green- 

 sand, new red sandstone, and retl marl; to the south, slate-limestone 

 and sandstone, with spots along the coast of blue lias and other 

 limestones, with mica and other slates. How interesting would be a 

 knowledge of the species peculiar to each of these formations ! To 

 which of them is it that we owe the sudden extension and increase of 

 Caradrina amhigua ? 



But it is in Yorkshire that the most herculean task is to be 

 found: — to allot the 1340 species to their proper soils ! A county of 

 complicated and extraordinary geology, the formations placed mainly 

 in parallel strips running in some degree north and south. Com- 

 mencing on the eastern side, the southern half is broadly composed of 

 land recovered from the sea, formerly salt-marsh, now pastures ; to the 

 west of this is the great baud of chalk already alluded to, with its 

 usual narrow border of greensand ; north of it alternate bauds of 

 oolite, coral-rag, and lias, or closely allied formations, the latter also 

 baunding the greensand and other bands already alluded to ; west of 

 this are succeeding broad bands of new red sandstone with its allied 

 formations, magnesian limestone, millstone grit, and coa,l measures. 

 There is magnificent work for my friend Mr. Porritt, if he will take 

 it up ! 



These are mere suggestions, roughly thrown out ; it would be easy 

 to extend them. Other formations, besides the chalk and the oolite, lie 



