238 TUREITELLA. 



Turritella acricula, Tate. 



1893. Turritella acricula, Tate, Trans. Eoy. Soc. South Aust. vol. xvii. 

 pt. 2, p. 339, pi. viii. fig. 4 ; pi. ix. figs. 4, 7, 12. 



This variable species may be distinguished by its slender 

 lanceolate form, by the large number of whorls, amounting to 

 twenty in typical forms of the adult, and by their flatness. 

 Commonly there are from fifteen to twenty spiral lines of unequal 

 size, the larger ones forming lirse or carinae, which latter may be 

 from two to five in number, the largest bordering the suture 

 anteriorly. The variation consists principally in the mode of 

 development of the spiral ornament and the consequent change 

 in shape of the whorls. 



It is closely related to T. acuta, Tenison-Woods [non Mayer), 

 a species living in South Australia and Tasmania, but the fossil is 

 relatively narrower, and the spiral lineations and carinae are more 

 numerous. 



Dimensions. — Length 27 mm. ; breadth 6 mm. 



Form, and Loc. — Eocene : Kiver Murray cliffs, South Australia. 



G. 9429. Examples illustrating stages of growth ; one shell 

 is narrower than the others, the usually prominent spiral carina 

 being much reduced in size. Purchased. 



Turritella aldingse, Tate. 



1882. Turritella aldingce, Tate, Trans. Roy. Soc. South Aust. vol. v. p. 42. 

 1893. Turritella aldingce, Tate, id. vol. xvii. pt. 2, p. 336, pi. viii. fig. 1. 

 1895. Turritella aldingce, Tate and Dennant, id. vol. xis. pt. 1, p. 112. 



Shell pyramidal, spire acute ; whorls flat, furnished with three 

 prominent, unequal, spiral carinae, and distant spiral striae ; lines 

 of growth conspicuous, deeply sinuated, producing rugosity, and 

 granulating the medial keel; suture incised; aperture (according 

 to the author of the species) subquadrate, margins united by a 

 somewhat thick callus, which extends over much of the flattened 

 forepart of the shell; columella arched; outer margin somewhat 

 flatly compressed, and deeply and broadly sinuated. Its pyramidal 

 shape, the granulose median keel, and the deep sinus, serve to 

 readily distinguish this from T. warlurtoni and T. conspieahilis. 



