NEWTON: NEW BRITISH EOCENE GASTROPODA. 327 



aperture acutely ovate, oblique, anteriorly wide and laterally expanded ; 

 columella with a strongly twisted fold, having behind an obscure 

 umbilical perforation ; labrum acutely margined and bearing interiorly 

 eight prominent, ridge -like, equidistant plications. Dimensions: alt. 4, 

 diam. 2 mm. 



This species is characterized by the small number of its volutions, 

 by the great size of the body- whorl, and by the plications on the inner 

 surface of the labrum. The French Eocene forms of this genus, such 

 as 0. minor, Desh., 0. hordeola, Lam., or 0. pyramis, Desh., show 

 the same sculptured character of the labrum, though at the same time 

 they possess a greater number of whorls than the English form. It is 

 perhaps more closely allied to 0. Lapparenti, De Raincourt, from the 

 Paris Basin, which is also ventricose, though having more plications in 

 the labrum and a less prominent fold on the columella ; it also differs 

 from 0. pingue, Von Konen, of Oligocene age, from North Germany, 

 in its much longer body -whorl and in its general contour and size. 



This is apparently a rare species, only one or two examples being 

 known. 



Formation. — Upper Eocene (Barton Beds). 



Localities. — Barton (type) and High Cliff, Hants. 



Cancellaria microstoma, n.sp. PI. XXII, Pigs. 3, 4. 



Cancellaria microstoma, Charlesworth MS., Morris, Cat. British 

 Fossils, 1854, ed. 2, p. 239; R. B. Xewton, Syst. List 

 Edwards Coll. British Museum, 1891, p. 171. 



Shell small, elongate, umbilicated ; apex obtuse ; consisting of six 

 moderately convex and deeply sutured whorls, the two initial ones 

 being smooth, the remainder strongly marked with varices and encircled 

 by regular concentric lines ; last whorl rather longer than half the 

 entire axis of shell ; aperture small, oval, with a short, naiTow, and 

 slightly curved anterior canal ; labrum thickened by the last varix, 

 serrated, with a feeble anterior sinus, and bearing five or six elongate 

 plications on its inner surface ; columella border callous, reflected, 

 possessing two nearly horizontal plaits ; umbilical cavity infundi- 

 buliform, small and radiately striated. Dimensions : alt. 7 mm. ; 

 diam. nearly 4 mm. 



Several examples of this species, occurring in both Barton and 

 Bracklesham deposits, are represented in the British Museum, so it 

 may be regarded as fairly common. It differs from Cancellaria 

 evulsum (Solander), found in similar beds, in having two instead of 

 three columella plications, in possessing an umbilicus, in its narrower 

 anterior canal, and in being furnished with fewer plications within 

 the labrum. From the French specimen C. Bezanconi, De Raincourt, 

 it is also removed by reason of its smaller aperture, its curved canal, 

 and the presence of the sinus on the outer lip. 



The genus Cancellaria has been specially studied by such authorities 

 as Adams, Jousseaume, Sacco, etc., who have divided off its many 

 species under various genera. The present form might be recognized 

 as belonging to M. Cossmann's sectional group of Sveltella, though 

 temporarily I prefer to regard it as a true Cancellaria. 



