DENTALnnn. 295 



is lianlly a specific characteristic. D. gtganieum is closely related 

 to D. mantelli, but the tessellated ornament of the latter, amongst 

 other things, is highly distinctive. 



Dimensions. — Length 109 mm.; width of anterior aperture 

 12 mm. 



Funn. and Loc. — Miocene and Pliocene : New Zealand. 



G. 10251. Many examples imbedded in blocks of argillaceous 

 shelly limestone ; from Akuakua, east coast of Auckland. 



Sir James Hector Coll. 



G. 10256. Two fragments ; from Kanieri, South Island. 



Sir James Hector Coll. 



G. 10257. Specimen constricted at irregular intervals ; from 

 Hick's Bay. Sir James Hector Coll. 



G. 10259. An example of the adult having closely-set longi- 

 tudinal sulci and ridges ; from Parimoa. W. B. D. Mantell Coll. 



Dentalium bifrons, Tate. 



1887. Dentalium bifrons, Tate, Traas. Roy. Soc. South Aust. vol. ix. p. 192, 



pi. XX. fig. o. 

 1893. Dentalium bifrons, Tate and Dennant, id. vol. xvii. pt. 1, p. 223. 



Shell large, but slightly curved, longitudinally ribbed or striated 

 at the posterior end, smooth at the anterior ; the striiB are small 

 and close together, and gradually die out at about one-third the 

 length of the shell, where annular rings of growth become a marked 

 feature, and obtain to the anterior aperture. The posterior fissure, 

 wliich does not appear to have been known to Professor Tate, is 

 several millimetres in length and twisted, running obliquely with 

 reference to the longitudinal costae alluded to. 



The ornament of the striated portion is not tessellated as in 

 D. mantelli; whilst the posterior end of D. anmdatum, Tate, with 

 which this species is related, is not costate, and the shell is 

 narrower anteriorly. 



Dimensions. — Length 74 mm. ; width of anterior aperture 8 mm. 



Form, and Loc. — Miocene : Muddy Creek, Victoria. 



G. 4282. Three examples, one having a nearly perfect apex, 

 with clearly-marked fissure. Presented by John Dennant, Esq. 



