120 



PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



Form, and Loc. — Inferior Oolite (co?icavus -zone) : Bradford Abbas, 

 Dorset. 



Mr. S. S. Buckman has examined these specimens and considers 

 'No. C. 4256 to be from " (probably lower part of) concavum-zone " ; 

 No. C. 3177, from the "fossil bed (probably concavus-hed)'' ; and 

 !N"o. C. 4503, from the '^concavum-zone (^probably Hi/perlioceras-hed).^^ 



2. IS'AtrTiLus OBSTETJCTUS, E. Eudes-Deslongchamps. Fig. III. 



Nautihis obstruetus, E. Eudes - Deslongchamps : Jura Normand, 

 Monog. vi (1878), pi. xi, figs, la-d, 2a-c. 



Specific Characters. — Shell inflated, somewhat rapidly increasing, 

 with broad periphery; greatest thickness (at the aperture) at about the 

 commencement of the outer third of the lateral area, about three- 

 quarters of the diameter of the shell ; height of outer whorl about five- 

 eighths of the diameter of the shell. Whorls (number unknown) ; 

 inclusion complete ; umbilicus closed. "Whorl trapezoidal in section, 



Pig. III. — Nautilus obstruetus, Eud.-Desl. a, lateral view, showing on the natiural 

 internal cast of the body -chamber the anterior boundary of the muscular 

 impression ; b, front view of the same. Inferior Oolite [Parkmsoni-zone) : 

 Vetney Cross, Dorset. Drawn from a specimen in the British Museum 

 Collection [C. 3187]. Two-thirds natural size. 



its height five-sixths of its width, the widest j)art being near the 

 umbilicus in the septate part of the shell, but near the periphery at 

 the aperture ; indented to about two-fifths of its height by the pre- 

 ceding whorl ; periphery broad, flattened, slightly convex in the 

 septate part, slightly concave on the body-chamber; sides feebly 

 convex, except near the aperture, where they are more inflated ; no 

 inner margin. Body-chamber occupying rather more than one-third 

 of the last whorl ; aperture forwardly inclined, lateral portion of 

 peristome convex orad, its peripheral portion with a deep wide 



