200 



NOTES ON SOME NEW ZEALAND PLEUROTOMID^. 

 By Heney Sutee. 



Eead Wth November, 1904. 



There has been considerable confusion about three species, viz. : 

 Pleurotoma Buchmmni, Hutton, 1873; Pleurotoma Trailli, Hutton, 1873 ; 

 and DrilUa{^) Maorum, E. A. Smith, 1877. I have hitely been 

 studying these forms, and propose the following towards an elucidation 

 of the complication : — 



1. SuRCULA BucHANANi, Huttou, subsp. Maorum, E. A. Smith. 



Drillia (?) Maorum, E. A. Smith : Ann. Mag. Nat. Hist. (4), vol. xix 



(1877), p. 497. 

 Drillia Buchmiani, Hutton : Journ. de Conch., vol. xxvi (1878), p. 16 



(not of Cat. Tert. Moll.). 

 Pleurotoma Buchanani, Hutton: Man. N. Zeal. Moll., 1880, p. 42 



(not of Cat. Tert. Moll.). 

 Drillia Maorum, Hutton : I.e., p. 44. 

 Pleurotoma Buchanani, Tryon : Man. Conch. (1), vol. vi, p. 208 (not 



of Cat. Tert. Moll.). 

 Drillia (?) Maorum, Hutton: Proo. Linn. Soc. N.S. Wales (1), vol. x 



(1886), p. 116. 

 Surcula Trailli, Suter : Trans. N. Zeal. Inst., vol. xxxi (1899), p. 90 ; 



I.e., vol. xxxiv (1902), p. 211 ; Index Faunae Nov. Zeal., 1904, 



p. 71. 



There can be no doubt that E. A. Smith's D. Ifaorum is very much 

 like P. Buchanani, Hutton, of the Cat. Tert. Moll., but it is not 

 absolutely the same. The former is more slender, the whorls in 

 consequence appear rather higher, the width of the body-whorl is 

 less, and the canal is shorter. The margination of the suture is 

 generally, but not always, slighter. The special sculpture and the 

 nuraber of longitudinal costae are somewhat variable in both species. 

 The angle of the spire I found on an average to be 29° in Maorum, 

 and 32° in the Pliocene Buchanani. Carefully taken measurements 

 of the two species gave the following result : — 



Maorum. Buchanani. 



Total length 



Length from base to middle of first suture . 



Length of aperture 



Length of spire 



Width of bo ly- whorl 



