146 DEVONIAN FAUNA. 



described a totally different species under the same name. In 1837 Phillips,^ in 

 the ' Geology of Yorkshire,' described a fossil under the name 0. undulatum, 

 Sowerby, which, however, Mr. Foord identifies with 0. striatum, Sowerby.^ In 

 the naming of his plates Phillips substituted the name of 0. laterale for Sowerby' s 

 name without explanation. However, in 1841 he described and figured the 

 present species under the name 0. laterale,^ identifying it with the Yorkshire 

 • shell, and stating that he discarded Sowerby's name because it was " given by 

 foreign authors to a different and well-known species." Portlock tries, not very 

 successfully, to remove the confusion ; pointing out that the siphunclein Sowerby's 

 shell is marginal, he leaves Phillips's name for that, and gives a new name, 0. suh- 

 imhricatum,^ to another Carboniferous specimen, which he supposes to be the same as 

 Phillips's." This, however, differs from the Devonian form by having " undulating 

 lines parallel to the septa," and hence Portlock's name cannot, under any circum- 

 stances, be retained for it. There can be no doubt that Phillips's name should 

 properly be applied to his own specimens, and not to Sowerby's, which, indeed, have 

 received a new designation, Actinoceras Soiverbyi, from M'Coy.^ It appears, however, 

 that Sowerby's name has the priority over Schlotheim's, and therefore ought to be 

 retained for his species, A. undvlatum. Again, as Philhps's Yorkshire shell is the 

 same as another of Sowerby's species, his names for that must be replaced by 

 its original name, A. striatum, Sowerby, sp.^ But we have seen that the name 

 0. laterale was only vaguely attached to the figure of the Yorkshire shell, and that 

 the first time a species was definitely described under it was in the case of the 

 Devonshire fossil. To this species it has generallly been regarded as belonging 

 by succeeding authors, e.g. Bronn,''' Foord. Under these circumstances it seems 

 best to regard the description in the ' Paleeozoic Fossils ' as its authoritative 

 definition, and to retain Phillips's name, 0. laterale, only for the Devonian shell, 

 especially as it will be seen that there are not very decisive grounds for deciding 

 the identity of the foreign species which appear to correspond with it. 



It may be observed that it is clearly distinguished from the two above- 

 mentioned species, A. striatum, Sow., sp. {^= undulatum, Phil.), and A. undulatum^ 

 Sow., sp. (= A. Sowerbyi, M'Coy), by the small size and the central position of its 

 siphuncle. 



0. Grundense, Trenk., as figured by Clarke^ may well be the same species, 



1 1837, Phillips, ' Geol. Yorkshire,' vol. ii, p. 251, pi. xi, fig. 1. 



2 1888, Foord, ' Cat. Poss. Ceph. Brit. Mus.,' vol. i, p. 190. 



3 1841, Phillips, ' Pal. Foss.,' p. 110, pi. xli, figs. 205 a—e. 

 * 1843, Portlock, 'Kept. Geol. Londonderry,' p. 391. 



5 1855, M'Coy, ' Brit. Pal. Foss.,' pt. 3, p. 573. 



« 1814, Sowerby, ' Min. Conch.,' vol. i, p. 129, pi. Iviii. 



^ 1848, Bronn, ' Index Pal.,' vol. iii, p. 8G5. 



8 1884, Clarke, ' Neues Jahrb. fiir Min.,' Beil.-Band iii, p. 334, pi. vi, figs. 7—9. 



