ALARTA. 135 



54. Alaeia Lorieri, D'Orb., var. gracilis, Lycett, 1853. Plate VI, fig. 5. 



1853. Rostellarta GitACiLis, Lycett. Proc. Cotteswold Nat. Field Club, vol. i, 



p. 80. 



Description. — " Spire lengthened, smooth. Whorls six, lengthened, angulated, 

 the angle being in the middle of the whorl, forming an acute and crenulated 

 carina ; body-whorl smooth, with two carinas and large digital processes ; caudal 

 extremity slender and lengthened. The slender form, crenulated carina, and 

 smooth surface distinguish it from B. triftda." — Lycett. 



The figured specimen, which is believed to be Lycett's type, presents no 

 crenulations other than the result of usage, and this is also the cause of the 

 smoothness, the spiral lines having been rubbed down almost to obliteration. The 

 appearance of smoothness in fossils obtained from oolitic freestones is in most 

 cases merely due to rolling. The " caudal extremity " is not particularly lengthened, 

 and there are indications in the specimen of the commencement of the hamicaudal 

 curve. The mean spiral angle is about 28°. 



Relations and Distribution. — This variety is more slender than the majority 

 of the specimens referred to Al. Lorieri from the Parkinsoni-zone of Burton 

 Bradstock. It may, in fact, represent the typical Al. Lorieri of D'Orbigny. 



There is a particular interest attaching to the figured specimen, viz. that it 

 is the earliest recorded example of the trifida-grouip in this country. It was 

 obtained from the Freestones below the Oolite-Marl near Leckhampton, which are 

 well within the Murchisonce '-zone. Such fossils must be extremely rare, since no 

 species of the trifida-growp is quoted from any horizon of the Inferior Oolite in 

 WitchelPs ' Geology of Stroud.' Since the few species of Alaria hitherto discovered 

 in the British Lias appear to belong to the Monodactyl section, this is the earliest 

 Didactyl Alaria known in this country. 



55. Alaria pontonis, sp. nov. Plate VII, figs. 1 a, I b, and var. spinifera, Plate 



VII, fig. 2. 



Description : 





Length .... 



. 22 mm. 



Width of body-whorl to height of shell 



. 50 : 100 



Spiral angle .... 



. 42° 



