﻿240 DEVONIAN FAUNA. 



? 1887. Euomphalus, cf. planobbis, Tschemyschew. Mem. Com. Geol. Ruas., 



vol. iii, No. 3, p. 171, pi. vi, figs. 5 a — c. 



1888. — planobbis, Etheridge. Foss. Brit., vol. i, Pal., p. 163. 



1889. — Whidborne. Geol. Mag., dec. 3, vol. vi, p. 30. 

 1889. Philoxene l^vis, Kayser. Zeitschr. Deutsch. Geol. Gesell., p. 292, pi. xiii, 



figs. 5, 5 a — c. 



Description. — Shell rather large, discoidal, flat, of four or five whorls. Spire 

 flat, the upper surface of the central whorls lying in one plane, but that of the 

 outer whorls tending more or less to become conical. Suture deep, vertical. 

 Whorls slowly increasing ; in section nearly circular, rising from the suture, 

 slightly elevated or subangulated at the shoulder so as to form a clear though 

 indefinite elbow; marked by fine, irregular, indistinct growth-lines. Shell- 

 structure rather thin, thickened at the shoulder. Umbilicus very large. 



Size. — Height 6 mm., width 20 mm. 



Localities. — From Wolborough there are two specimens in the Godwin-Austen 

 Collection in the Museum of Practical Geology, one in Mr Vicary's Collection, 

 and one in the Torquay Museum. From Lummaton there is a specimen in my 

 Collection, and two others in the Torquay Museum are probably from the same place. 



Remarks. — In 1842 d'Archiac and de Yerneuil described simultaneously two 

 shells, Eu. Ixvis and Eu. planorbis. The former of these exactly corresponds 

 with our figured English specimen. The other differs in several slight particulars, 

 but it seems to be the impression of Dr. Kayser, following Bronn, that these 

 differences are not of specific value, and he unites them into one species under 

 the name Ph. Ixvis. This view a comparison of the figures of the two species 

 leads me to consider perfectly correct ; the more so as we frequently find a con- 

 siderable amount of individual variation in other kindred species. 



There seems little reason for giving preference to either name. Its describers 

 place En. Ixvis before Eu. planorbis. The former they identify in their " Tabular 

 List," though not in their description, with Eu. Ixvis, Goldfuss, a catalogue name 

 for a shell which Goldfuss afterwards figured as Eu. serpens, Phillips, with which 

 it agrees. Bronn doubtfully unites them under the name Eu. planorbis. Other 

 authors have used the two names nearly equally. On the whole it seems best to 

 follow its describers in giving priority to Eu. Ixvis. 



Dr. Kayser formed his new genus for the reception of this shell because he 

 had observed that one or two German examples of it retained agglutinated 

 fragments of foreign shells. The same feature is occasionally to be observed, 

 though to a much slighter degree, in the English shells, and forms an additional 

 reason for concluding not only the generic but specific identity. 



The shell described by de Koninck under the name of Eu. planorbis from the 

 Carboniferous of Belgium differs so slightly that we may regard it as identical. 



