INTUODUCTION. 50;J 



THE WESTERN BASIN. 



St. Erth, "Wexford, Manxland. 



The true relation of the fossilifcrous deposits of the East Ang-lian Crag basin 

 to those of the western area, viz. of St. Erth on the one hand, and of Wexford 

 and Manxland on the other, has given rise to some difference of opinion. As 

 to the older of the three, those of St. Erth, S. V. Wood, jun., who first 

 described them in 1885, jnst before his premature death, ^ and Messrs. Kendall 

 and R. Gr. Bell, whose paper appeared a year later, regarded them as being 

 more or less equivalent to an early stage of the Red Crag.^ Grwyn Jeffreys and 

 the late Clement Reid,^ however, believed them to be older — a view which the 

 researches of Mr. Alfred Bell, given in two other papers, lead me to support.* 



A large number of specimens, many of them those left undescribed l^y Wood, 

 and some believed by Mr. Bell to be new to science, are now in the British 

 Museum. Some of these, with the kind permission of Dr. A. Smith Woodward, I 

 am able to figure in the present work ; others I may give hereafter. A con- 

 siderable number are minute forms belonging to genera such as Odostonda, 

 Tarbonilla, Eulima, Bissoa, etc. A few are larger and deserve here a passing- 

 notice, as, for example : 



*Nassa semireticosa, Btheridge and Bell, PL III, fig. 11. 

 „ soUda, S. V. Wood, MS., PI. XXXIII, fig. 22. 

 ,, mutahilis, var. erthensis, S. V. Wood, MS., PL XXXIII, fig. 26. 



*BittiiLiii retieulatam, var. trinodosa, Etheridge and Bell, PL XLI, fig. 4. 

 5, iiicile, Watson. 



*Tnryitella erthensis, sp. nov., PL XLII, fig. -1. 



Three of these, marked (*), are exceedingly common at St. Erth. They are 

 very distinct, and, so far as I can ascertain, are nnknown from any Miocene or 

 Pliocene deposit, either in England or elsewhere. 



Many of the characteristic and abundant groups of the Red Crag univalves, 

 moreover, are unrecorded from St. Erth, as, e. g., certain species of Nassa, Biiccinwm, 

 Ocinebra, Neptmiea, Sipho, Searlesia and Scala. Speaking generally, the mollusca 

 of the latter are not of a Red Crag type, northern shells being wholly absent. 

 At the same time it must be remembered that the area from which they have 

 been obtained is veiy restricted. Possibly other exposures will be discovered 

 hereafter which may throw further light on the subject. 



1 Quart. Jouni. Geol. Soc, vol. xli, pp. 65—73, 1885. 



2 Quart. Jouru. Geol. Soc, vol. xlii, pp. 201-215, 1886. 



2 " Pliocene Deposits of Britain," Mem. Geol. Surv., jjp. 59, 61, 62, 1890. 



* Proc. Eoy. Irish Acad. [3], vol. ii, pp. 620—642, 1883; Trans. Eoy. Geol. Soc. Cornwall, vol. xii, 

 pp. 111—166, pis. i— iii, 1898, 



