THE 



GEOLOGICAL MAGAZINE 



NEW SERIES. DECADE VI. VOL. IV. 



No. VIII.— AUGUST, 1917. 



ORIG-IUST .A.IL, ABTIC 



I. — Cretaceous Mollusca prom Ke\ 



By C. T. Teechmann, D.Sc, F.(\S' 

 (Concluded from the July Number, p. 

 (PLATE XXL) 

 Aplustruh (?) Sklwtnensis, sp. nov. (PL XXI, Figs. 1-3.) 



SHELL oval in shape, very thin, consisting of six whorls, the last 

 one very large and inflated. In some specimens the spire is rather 

 prominent, in others slightly depressed with rather deep sutures. 

 The apex and protoconch when not broken off are pointed and 

 prominent. The aperture is broad in front but narrow behind, and 

 seems to have a faint shallow anterior channel. There is no 

 columellar fold. The outer lip in specimens where it is preserved is 

 sharp and very slightly flattened out and expanded anteriorly. The 

 growth-lines are fairly prominent, and there is a tendency for faint 

 and shallow parallel furrows to develop, especially on the anterior 

 portion. Height about 18 mm. 



This fragile shell is rather common, but often more or less crushed. 

 Aplustrum is the only genus to which I can refer it, but compared 

 with a recent specimen of A. amplustre it has a more prominent 

 protoconch, which in the recent form is rather sunken and buried. 

 The shell of the recent form also is smoother and more glossy. 



Wilckens illustrates a shell {Bulla subglobosa) l viewed from the 

 mouth side, from Quiriquina, which recalls the present form if seen 

 in a similar position and may possibly be identical. It cannot, 

 however, be a true Bulla as he says the spire is only slightly 

 depi'essed, while a characteristic feature of Bulla is the deeply sunken 

 and hidden spire. 



I have also compared my specimens with the original illustrations 

 of Bulla subglobosa and Philine chilensis of Philippi 2 and find that 

 they do not resemble the figures of either, as in both of them the last 

 whorl appears more swollen and the spire more sunken. It also 

 recalls Bulla glacialis, "Wilckens, 3 from the Tertiary beds of Seymour 

 Island, Antarctica, which, as Wilckens remarks, is very like though 

 more swollen than B. subglobosa of the Cretaceous of Quiriquina, but 



1 N.J. fur Min., Beil. Bd. xviii, pi. xviii, fig. 11, 1904. 



2 Tert. u. quart. Versteinerungen Chiles, 1887, pi. xiii, figs. 2a, b, 4. 



3 "Die Mollusken der Antarkt. Tertiarformation " : Wissensch. Ergebn. der 

 Schwed. Sudpolar Exped., p. 29, pi. i, figs. 3Qa-c, 1911. 



DECADE VI. — VOL. IV. — NO. VIII. 22 



