488 REV. a. F. WHIDBOENE ON SOME FOSSILS 



dant in Dorsetshire. The large size of the mollusca at Dundry 

 is very noticeable in the field. 



In the highest part of the Humphriesianus-zone at Dundry very 

 numerous nodules occur of a more or less egg-shaped form. These 

 I at first thought to be sponges ; but, upon having them tested and 

 sliced for microscopical examination, Mr. Sollas could find in them 

 no clear remains of structure. They consist of fine marly limestone, 

 have a well-defined rounded surface with one or two deep depressions, 

 and appear generally to have a coral as nucleus. In spite of finding 

 no structure, I cannot help believing them to be of organic origin, 

 either allied to the Nullipores or some such growths as we now so often 

 find about low-water mark. If so, they would indicate still further 

 the depth at which the deposit was formed. 



In the following descriptions I have confined myself almost ex- 

 clusively to the Lamellibranchs. Having been permitted by Prof. 

 Sollas to study those in the Bristol Museum, several species among 

 them seemed to me undescribed ; and I was confirmed in this opinion 

 by the fact that the late Mr. Tawney, when he had arranged these 

 shells a few years before, had left them without names. After this 

 I was enabled, by the kindness of Dr. Woodward, Mr. Etheridge, and 

 Mr. E. T. Newton, to examine the shells from the same strata in the 

 British and Jermyn Street Museums, and there found some additions 

 to the list. Other species are from my own collection. To these 

 bivalves I have added one or two other fossils that appeared to me 

 of interest. I am under great obligations to Mr. Etheridge, E.R.S., 

 and other friends for assistance in respect to several of the following 

 species, and to Mr. Foord, E.G.S., for the careful drawings which 

 accompany this paper. 



AtfCYLOcERAs Waltoni, Morr. Plate XIX. fig. 1. 



1845. Ancyloceras Waltoni, Morris, Ann. & Mag. Nat. Hist. vol. 

 xv. t. 6. fig. 5. 



1845. ? A. costatus, Morris, Ann. & Mag. Nat. Hist. vol. xv. t. 6. 

 fig. 4. 



1849. A. subannulatus, D'Orb. Pal. Er. Amm. Jur. t. 225. figs. 8, 9. 



1881. A. subannulatus, Buckman, Q. J. G. S. vol. xxxvii. p. 607. 



D'Orbigny gives Morris's two species as synonyms for A. annu- 

 latus(Desh.); but as his chief reason for separating his A. subannulatus 

 from the former shell appears to be the permanence of the ribs on 

 the dorsal side, and as this is very decidedly seen in the form which is 

 common at Burton Bradstock, there seems to be no reason for sinking 

 Morris's name. "Whether his two species are not different portions 

 of the same shell would seem more doubtful, both from an exami- 

 nation of specimens and a comparison with D'Orbigny's fine figure 

 of the kindred A. annulatus. Morris, in the second edition of his 

 Catalogue (1854), unites the two species; Buckman {he. cit.) in. 1881 

 again separates them. 



Toxoceeas Oebignyi, Baugier & Sauze. Plate XIX. fig. 2. 



1843. Toxoceras Orlignyi, Baug. & Sauz. Not. sur quelques Ooq. 

 t. 3. fig. 18. 



