480 Correspondence — Dr. Wheelton Hind. 



three distinct tj'pes, each being represented by forms which have 

 attained the Dalliniform loop-stage of Beecher, viz. Coptothyris, 

 Macandrevia, and Dallina. Tiiese three genera are also characterized 

 by distinct types of beak characters, dental plates, etc. Thus three 

 evolutionary stocks can be clearly recognized, in each of which 

 Dalliniform loops have been attained by parallel evolution. There 

 appear to be other stocks present, but in these there is as yet no 

 evidence for the separate attainment of tlie Dalliniform loop. 



The study of the hinge characters of the species of Dallininse 

 contained in my collection (comprising most of the known forms) has 

 revealed manj' interesting features which have an important bearing 

 upon the classification of both recent and fossil forms. For some of 

 these forms it will be necessary to create new genera. 



J. Wilfrid Jackson. 



Manchester Museum. 



Septemher 4, 1918. 



THE CANINIA-SEMINULA HOEIZON OF PRODUCTUS 

 HUMEROSUS. 



Sir, — I have just received my copy of tlie Q.J.G.S., containing 

 Mr. Parsons' most excellent paper "On the Carboniferous Limestone 

 -of the Leicester Coalfield ". I want to ask him to reconsider the 

 question of the horizon of the beds containing Productus huinerosus 

 {P. subltBvis). Following Professor Sibly, who referred the Cauldon 

 Low (Staffs) Limestones to Dj, he has not pointed out that 

 P. humerosus is an important zonal fossil both in Belgium and the 

 Clitheroe area, indicating a Caninia-Semmula horizon. Therefore, 

 one must pause to think before beds containing it are assigned to 

 a much higher zone. The palaeontological evidence of the Cauldon 

 Low beds is strengthened by the presence in them of other members 

 of the C-S-^ fauna. Papillionaceous Chonetes, Bellerophon cornuarietis, 

 and other members of that genus, and several large Gasteropods 

 which can be matched in Belgium and Clitheroe. I note that 

 Cyrtina septosa occurs with P. humerosus. This, too, indicates the 

 lower zone. 



Then, again, the barrenness of the beds and the absence of 

 Lithostrotion and a Pibu7iophyUiiin fauna are very noteworthy. 

 I have, no doubt, in my own mind that the Cauldon Low beds are 

 of Caninia age, and the whole question will be more fully discussed 

 in a forthcoming paper on the Clitheroe area. 



Wheelton Hind, M.D., B.S., F.R.C.S. 

 On Service. 



Septemher 7, 1918. 



STEATIGEAPHICAL POSITION OF THE COEALLINE CEAG. 



Erratum. — In Mr. F. W. Harmer's article in the September 

 Xumber, " Stratigraphical Position of the Coralline Crag," p. 410, 

 for Walton horizon read Oaldey horizon = Poederlien, and for Oakley 

 horizon read Walton horizon = Sealdisien — the names Walton and 

 Oakley having been reversed. 



