1867.] SALTER AND HICKS LINGULELLA. 341 



Yar. a. ovalis, Hicks. Figs. 2 & 3. 



Shell ovate, 1\ line long : front edge rounded, not obtuse. 



Loc. Eed Eocks of the Menevian group, near St. Davids. 



Except the shape of the front edge of this small shell, which is 

 rounded off, and not squared at all, this variety is not to be dis- 

 tinguished from the other. 



We give this variety a distinct varietal name, as it is important to 

 distinguish all marked forms. When there is a difference in geological 

 position, as well as some peculiarity in the form, it is wiser to dis- 

 tinguish, at least as a variety, any important specimen. Until it 

 shall have been clearly proved, by intermediate forms, to belong to 

 the self-same species, there can be no reason for allowing a theo- 

 retical opinion of descent with modification to influence us, as 

 naturalists, in determining the nomenclature of a fossil or recent 

 shell. And the contrary proceeding would throw all our useful 

 binomial or trinomial appellations into oblivion ; while it would not 

 advance by one iota the real study of the group to which the fossil 

 belongs. 



That Lingidella ferruginea, var. ovalis, may have been the pro- 

 genitor of the more ordinary variety, which is found in rather newer 

 beds, is probable. That both may be only steps in the series by 

 which we at last reach, through several Lower Lingula-flag species, 

 the characteristic Lingulella Davisii and L. lepis of the Ffestiniog 

 and Tremadoc groups, is also possible, if not highly probable. But 

 we have no proof of it. Still less have we any proof that Lingulella 

 merges into Lingula, or this into Oholella, or the last into Discina, 

 &c., or that any or all of them had some common ancestor of whose 

 nature lue Jcnow nothing. 



I only intend by these remarks to show the importance of still 

 adhering, in our nomenclature, to old and well-established rules. 

 Whatever may be our theory as to the derivation of species, it 

 behoves us, as descriptive naturalists, to keep our minds free from 

 the delightful fetters of theory, while we strictly and truly describe 

 the medals of creation as they are shown to us. 



I think my friend Mr. Davidson, in whose acumen and talent I 

 have profound confidence, has of late years set us a bad example in 

 this particular. He merges Lingulella in Lingula (though one has a 

 pedicle -groove, and the other has not), and Trematis in Discina 

 (though one has a marginal foramen and a radiated surface, and the 

 other a closed foramen, and a homy concentrically ribbed shell). 



I may mention, while speaking of fossils from the Lower Cam- 

 brian rocks, which I regard as a portion of the great Menevian group, 

 that Mr. Alfred Marston, of Ludlow, has within the last few years 

 found other portions of the so-called Palceopyge, or some allied crus- 

 tacean form. They are in the truly rich museum in Jermyn Street. 

 He has also lately sent me word that my small Arenicolites are 

 not the only tenants of the Longmynd. A large worm-tube, com- 

 parable to the Histioderma of the Wicklow rocks, has been found in 

 the Longmynd by him. — J. W. S. 



