66 BRITISH CARBONIFEROUS BRACHIOPODA. 



limestone of Lowick, Northumberland, Malham Moor, about Berwick-on-Tweed, also in 

 Pembrokeshire, &c. In Scotland, Dr. Fleming has collected the shell at Dreghorn and 

 Ayr. Mr. H. Miller found it at Dryden, near Edinburgh, and Courland, near Dalkeith. 

 It occurs also at Carluke and Balquarhage, near Campsie. In Ireland it is also very 

 abundant. Mr. Kelly furnishes us with the following localities : Lisnapaste, Ardagh, 

 Little Island, Millecent, Larganmow, Tornaroan, Armagh, and Bannaghagole. 



The var. eUiptica occurs in many localities along with the more common varieties of 

 lincata, at Holland and in the lower carboniferous limestone of Kendal, Westmoreland, at 

 Millecent, in Ireland, &c. 



Sp. lineata and its variety, elliptica, are also very common shells in many foreign 

 carboniferous localities. Professor de Koninck names Vise, Males, near D'Ath, at Lives 

 and Chockier, in Belgium ; at Ratingen, &c. In the Geology of Russia, M. de Verneuil 

 and Count Keyserling mention Podolie, Sterlitamach, Sarana, Simsk, Becheva, &c. In 

 America it has been found in several localities, such as Keokuh, Iowa. 



Sub-Genus — Cyrtia, Dalman, 1827, and Cyrtina, J)av., 1858. 



In the eighty-third page of my general introduction doubts are expressed as to the 

 value of Dalman's Cyrtia, and his diagnosis is there stated to be unsatisfactory and 

 equally applicable to several species of Spirifer} In fact, the genus appears to have 

 been created simply to receive those few species of Spirifer which possess a circular foramen 

 in the deltidium of the larger valve, for the author did not furnish us with any information 

 regarding the internal arrangements of his two named types, C. exporreda and = C. 

 irapezoidalis. Subsequently to 1827 several other species were added (by different authors) 

 to the genus Cyrtia, and among these are some whose shell structure has been stated to 

 be punctate, while that of Dalman's type is unpunctate, as in Spirifer proper, and although 

 it has always appeared to me probable that a difference in shell structure would be 

 accompanied by some important interior modification, it was not until very lately 

 that I was enabled to discover some of the characters of the following species : 1, 

 C. exporreda ; 2, C. irapezoidalis ; 3, C.Murchisoniana;^, C. cuspidata ;h, C.heteroclyta ; 

 6, C. Bemarlii and C. septosaJ' The results of my examination will show that in the first 

 four, which belong to Dalman's genus, the internal characters are similar, but different 

 from the last three, which cannot be properly retained under the same generic denomination, 



' As we progress with our investigations, and as obscure points are gradually made clear, it is some- 

 times necessary to correct or to modify conclusions which may have resulted from the study of imperfect 

 or insufficient material. 



2 As I have had no opportunity of studying the interior of the other species classed with Cyrtia, it will 

 not be necessary to mention their names in the present instance. 



