neighbourhood of Cirencester. 327 



phic Society), are all referable to one species ; this is a fact ar- 

 rived at by a comparison of hundreds of individuals, and that 

 the author just cited seems to have almost arrived at when he 

 says, in his description of T. lagenalis, " This species has little 

 to distinguish it from T. ornithocephala, into which it seems to 

 merge by insensible passages," p. 42. As regards T. sublage- 

 nalis, the same author remarks, " This species is always accom- 

 panied by T. lagenalis, of which it may perhaps only be a va- 

 riety," p. 43 ; and further, " It is not difficult to find species 

 uniting ornithocephala to lagenalis, and this last to sublagenalis ; 

 but as the typical shapes of each are well distinguishable, it 

 will be found convenient to retain them under distinct specific 

 names." The Terebratula digona, he says, " often approaches in 

 general form and convexity certain specimens of T. obovata." 



Here then a wide subject for discussion seems to be opened 

 up ; for if we are to found specific names upon typical specimens, 

 the question is, where are we to stop ? certainly in the case before 

 us, not with five species. And again, if we admit the specific 

 identity of the five types under discussion, is it not probable that 

 even these are but derivative forms that may, in like manner, 

 be identified with others ? Our own materials certainly tend to 

 this conclusion. 



In this district the five forms quoted, though not altogether, 

 yet for the most part, afiect distinct localities ; hence the T. la- 

 genalis and sublagenalis will be found congregated in masses in 

 the Fairford quarries, while the T. obovata, from being a rare 

 exception with them, becomes the rule between Cirencester and 

 Cricklade. All these, however, ai-e at Malmsbury replaced by 

 the T. digona, which, as yet, is the only instance in this district 

 in which I have observed the latter shell strapng from the 

 Bradford Clay, of which I have been used to consider it charac- 

 teristic. 



The only remaining Brachiopod I shall here mention will be 

 the T. intermedia, ' Min, Conch.' 1. 15. f. 8 : this is undoubtedly, 

 to say the least, a form of T. perovalis. This opinion again is 

 borne out by Mr. Davidson, as he says in his Memoir, p. 53, 

 " Ter. intermedia bears some resemblance to T. perovalis ; some 

 specimens are undistinguishable." Now as this latter is an 

 abundant fossil of the Inferior Oolite as w^ell as Cornbrash, the 

 sequel will show its recurrence to be of great interest. 



Our next remarks will be upon the Conchifera, the chief in- 

 terest of which will be found in the fact, that in our summary of 

 fifty species, twenty-one or nearly half can be identified with 

 Inferior Oolite shells, and those for the most part of individuals 

 which have always been held as highly characteristic of the Lower 

 Oolite beds ; this will become apparent from the following 



