PLEUROTOMARIA. 431 



372. Pleurotomaria ornata-depressa, sp. nov. Plate XXXIX, figs. 3 a — c. 

 Cf. Cirrus carinatus, Sowerby. Min. Conch., pi. ccccxxix, figs. 3, 4. 



Description : 



Height . . . . .14 mm. 



Basal diameter . . . .40 mm. 



Spiral angle ..... 135°. 



Shell turbinate, subdiscoidal, umbilicate. Spire regular. Whorls (about five) 

 angular and discoidal ; sutures strongly canaliculate. The spiral ornamentation 

 is well developed, and, in addition, the crown of each whorl carries a zone of 

 undulating radial tubercles regularly disposed. 



The sinus-band is wide, median and flat, with traces of spiral lines, which, 

 however, are not seen anteriorly. The body-whorl is relatively large and similar 

 in character to the whorls of the spire, with an angular periphery and flatfish base 

 richly decussated ; umbilicus deep rather than wide. Aperture oval-depressed. 



Relations and Distribution.. — The figured specimen is from Bradford Abbas 

 most probably from the Coucavus-bed. Small depressed forms, with somewhat 

 similar ornamentation, occur in the Murcliixonse-zone of the Cotteswolds ; I also 

 possess a cast from Leckhampton which corresponds well with this figure. PL 

 ornata-depressa maybe regarded as the most depressed variety of the Omata-group. 

 A large specimen showing similar ornamentation, but with a rounder body-whorl 

 and rather higher spire, presents us with another variety of the Omata-group. 

 This is from Dundry. 



Note respecting Cirrus carinatus. — It will be remembered that this very 

 discoidal cast came from Leckhampton. Presuming that it is the cast of a 

 Pleurotomaria, this makes one of the three Jurassic species of which the actual 

 figured specimen is preserved in the Sowerby type collection at the British Museum. 



Unfortunately, the name " carinata," as applied to Pleurotomaria is bespoken 

 for a Palaeozoic fossil, viz. Pleurotomaria (Helix) carinata, Sowerby ('Min. Conch.,' 

 pi. x, upper and lower figures). 



373. Pleurotomaria Acttea, cVOrbicjnij, 1850. Plate XXXVII, fig. 8. 



1850. Pleurotomaria Act^a, d'Orbigny. Prod., i, p. 267. 



1854. — — — Tei*r. Jur., vol. ii, p. 459, pi. ccclxxv. 



1873. — — Tawney, Dundry Gasteropoda, p. 50 



(42). 



56 



