BAIRDIA SUBDELTOIDEA. 7 



1880, p. 55, pi. viii, figs. 1 and 2) is most comparable with B. suhdeltoideat and 

 that "it is very probable that several species are comprised under the specific 

 name subdeltoidea, as applied by various palseontologists ; the figures of that 

 species given in the works of Messrs. Bosquet, Jones, Speyer, Reuss, and Egger 

 presenting important points of difference among themselves." Of B. foveolata he 

 states, " This is one of the most abundant forms of Bairdia, especially in the 

 Southern Seas," and is subject to much variation. The recent form recognised 

 as B. subdeltoidea in 1866 (' Tr. Zool. Soc.,' vol. v, p. 365) was from Australia, the 

 West Indies, Crete, and Serpho. 



For the great variety of recent Bairdias, Dr. Brady's ' Challenger Report,' 

 1880, besides his other memoirs, can be consulted ; and a great variety of forms 

 occurring fossil in the Carboniferous and Permian strata are figured and described 

 in the ' Quart. Journ. Geol. Soc.,' vol. xxxv, 1879, pp. 565, &c. Some, however, 

 of these may possibly belong to other genera. 



A careful comparison proved the Tertiary species from Bracklesham (' Suppl. 

 Mon. Tert.,' p. 16) to be the same as Count Miinster's species, and there is no 

 dissimilarity at all between these and the Cretaceous specimens here figured. 

 Localities : 



Chalk : Norwich, Horstead, Colchester, and South-east England ; Cave Hill, 



(Antrim), and Keady Hill (Londonderry). 

 ChalJc-rocJc : Dunstable and Luton (Bedfordshire), West Wycombe (Bucking- 

 hamshire), Chinnor (Oxfordshire). 

 Chalk-marl: Didcot (Berkshire). 

 Detritus : Charing (Kent). 

 Gault : Godstone (Surrey). 

 Greensand : Cambridge and Warminster. 

 Foreign : 



Cretaceous formations : Royan, Maastricht, Riigen, Gehrden,^ Miinster, 

 Lemforde, Dresden, Weinbohla, Gosau, Dobrutscha. See also Reuss, 

 ' Elbthalgeb.,' pp. 140, 141, 153, for the localities. 

 We may remark that, as with other species, the geographical and geological 

 distribution of this form has to be revised and determined by reference to collec- 

 tions and late works, and is left for future consideration. 



1 For the localities of the several Cretaceous formations in North Germany see the Appendix to 

 Eomer's ' North-German Chalk-formation,' translated in Taylor's ' Scientific Memoirs,' vol. iv, 

 Article v. 



