18 APPENDIX 



Terebratulce with Short Loops — Tebebbatula Type. 



Page 45, Ter. punctata. Sow. sp., T. sub-punctata, and T. indentata. 



I am now ready to admit with Mr. J. Jones, of Glocester, that T. sub-punctata is only tiie adult 

 state of T. punctata, Sow., but am not yet prepared to say as much of T. Edwardsii. A dark longi- 

 tudinal line visible on the surface of the ventral valve, in several examples communicated by Mr. Moore, 

 indicating the presence of a mesial septum, led me to believe that this species was possessed of a lengthened 

 loop, while in T. punctata, Sow., I am certain that the loop was short. I will not, however, pretend that 

 I may not be mistaken relative to T. Edwardsii, it is a subject for further consideration. T. indentata 

 may, perhaps, prove to be nothing more than a variety of T. punctata, but I have never had at my disposal 

 a sufficient number of examples of the last to be able to decide the question. 



Page 48, Ter. simplex, Buckman, 1845. 



I am reminded by Dr. Wright, that Llwhyd had named and figured the present shell under the 

 appellation of Terebratula triangularis maxima ('Lith. Brit.,' 2d ed., 1699, p. 25, No. 870, tab. xxv, 

 fig. 870). I believe it is a very good species, and quite distinct from T. perovalis, Sow. 



Page 51 and 52, Ter. perovalis and Ter. intermedia, Sow. 



Professor Buckman states that " Ter. intermedia is undoubtedly, to say the least, a form of 

 T. perovalis." When describing T. intermedia, from the Cornbrash, I admitted that specimens of the last 

 bore much resemblance to certain forms of T. perovalis ; but I do not feel so confident as Mr. Buckmann 

 seems to be, as to the propriety of at present uniting the two under a single denomination. The Rev. 

 A. W. Griesbach states that, " there is, perhaps, more difficulty in speaking positively about T. perovalis 

 and T. intermedia. The difficulty of discrimination can only take place, when we have nothing before us 

 but half-grown specimens of T. perovalis ; when this species attains its full development, as it does in the 

 Inferior Oolite of Crickley Hill in Glocestershire, Dundry, Yeovil, Les Moutiers (France), &c, there can 

 be no doubt about it. So far as my experience goes of T. intermedia, and it has been very extensive (I 

 possess a large series of adult typical forms, both from the Cornbrash and Great Oolite), and have never 

 seen it lose the plication in the frontal margin and assume the form of the same margin, as seen in old 

 specimens of T. perovalis from Crickley, I therefore conclude T. perovalis and T. intermedia to be distinct 

 forms. 



Professor Bayle informs me, that from the material in the School of Mines of Paris, it is impossible to 

 distinguish young specimens of T. intermedia, T. maxillata, and T. Phillipsii, but admits that we can 

 easily recognise adult types of the three species, 1 an opinion with which I entirely concur, as it is evident 

 that the adult or full-grown state must give the character to the species, and not those intermediate con- 

 ditions, wherein the animal has not attained its full development. No one (I suppose) would think of 

 drawing up the characters of a species ofTrilobite, from the appearance of one of its metamorphoses. It 



1 " Je reconnais, comme vous, qu' on peut trouver trois types bien distincts pour y rapporter ces trois 

 especes ; mais dans les ages intermediaires, il y a veritablement impossibilite absolue a faire rentrer la 

 plupart des individus dans Fun plutot que dans l'autre des trois types : mais comme la determination 

 d'une espece exige toujours la connaissance precise de son developpement, s'il y a trois types adultes, il y a 

 trois especes, quoiqu'il ne soit pas possible de determiner avec certitude les jeunes." (Paris, 16 Juillet, 

 1854.) 



