194 E. Wilson — British Liassic Gasteropoda. 



the results of their labours has been to materially add to our know- 

 ledge of the Gasteropoda of the Lias formation. 



The following summarized account will serve to illustrate the 

 progress which has been made in this branch of Palseontolog}^ in 

 recent times. In the Catalogue of British Fossils (2nd edition), 

 published by the late John Morris in the year 1854:, only six species 

 of Gasteropoda are quoted from the Lias formation, viz. Pleurotomaria 

 Anglica, PI. compressa, PL expansa, Trochus imbricatus, Turbo 

 undidatus, and Dentalium giganteum. In 1872, twenty- three species 

 bad been obtained from the Lias of Yorkshire, but in 1876 this 

 number was, through the labours of Messrs. Tate and Blake, 

 increased to 89 (see "Yorkshire Lias," p. 331). Mr. E. C. H. Day 

 in 1863 obtained 40 species of Gasteropoda from the Middle Lias of 

 Dorsetshire, many of which were new to this country, and appear to 

 be confined to that district (Q.J.G.S. vol. xix. p. 278, and voL xxxiii. 

 p. 167). One of the most indefatigable students of the palfeontology 

 of the Lias at this period was the late C. Moore, who chiefly worked 

 in the Somersetshire and S. Wales areas. The fruits of the labours 

 of that very capable geologist are to be seen in the splendid " Moore 

 Collection " of Lias fossils in the Bath Museum. This collection, 

 which is, I believe, richer in Lias Gasteropoda than any other in 

 England, contains 180 named British species, including no less than 

 90 type forms, many of which are unique both in their interest and 

 rarity.^ In 1871 Prof. Ealph Tate, in his "Census of the Marine 

 Invertebrate Fauna of the Lias," enumerated 269 species representing 

 32 genera of British, as compared with 650 species representing 43 

 genera of Continental Liassic Gasteropoda (Geol. Mag. Vol. VIII. 

 1871, p. 4). Mr. R. Etheridge, F.E.S., in his Presidential Address 

 to the Geological Society in 1882, " On the Analysis and Distribution 

 of the British Jurassic Fossils," quotes 388 species, which are classed 

 by him under 51 genera, from the Lias of Great Britain. Of this 

 large number only six- species are stated to pass up into the Inferior 

 Oolite, viz. ActcEoriina pulla, AmherJeya capitanea, Cerithium papil- 

 losum, Natica adducta, Onustus pyramidatus, and Pleurotomaria 

 princeps, one of which (A. capitanea) survived into . the Forest 

 Marble (Q.J.G.S. vol. xxxviii. p. 165). In reference to the foregoing 

 account I would observe, without in any way questioning the general 

 accuracy of the figures given by my esteemed friend Mr. Etheridge, 

 or the validity of the conclusions founded thereon, that the number 

 both of the species and of the genera appear rather too high for what 

 they respectively represent. It was admitted, for instance, that the 

 136 Middle Lias names represented only 118 true species, and this, 

 apart from any similar deduction for duplicated nomenclature in the 



1 See Quart. Journ. Geol. Soc. vol. xxiii. p. 449, pi. 14-16; Proc. Somerset Arch, 

 and Nat. Hist. Soc a^oI. xiii. p. 119, pi. 4-6. It is unfortunate that these types 

 should have been so indiiierently delineated. Moore's sketchy figures give but a poor 

 idea of the beauty of these fossils, and, in several instances, are so inaccurate as to be 

 positively misleading as to their form. Students of this group should therefore beware 

 of too readily trusting to identifications founded solely on comparisons of their 

 specimens with these figures. 



2 This number is certainly capable of increase. 



