190 Transactions. — Zoology, 



Sec. TIOLOGNATHA. 



Jaw in one piece ; teeth arranged in nearly straight transverse rows on 

 the radula ; central tooth quadrate. 



Sub-sec. Aulocognatha. 



Marginal teeth quadrate, usually broader than long, and with several 

 small points. 



Farn. Helicidcs. 



Animal heliciform, with an external shell ; tail without any mucous 

 gland. 



Sub-fam. Buliminoe. 



Shell ovoid, conoidal or turreted ; the aperture longer than wide. 

 Genus Placostylus, Beck. 



Shell large, imperforate, rugosely striate ; the peristome thick and 

 expanded, the margins united by a callus. 



P. bovinus, Bruguiere (1785) [not B. auris-bovina, Beeve, f. 185, which 

 is B. lessoni, Petit, from New Caledonia] ; B. shongii, Lesson (1830) ; B. 

 fibratus, Gray in Dieffenbaclrs New Zealand, ii., p. 263 [not of Martyn]. 



Shell solid, oblong conical ; fulvous brown, occasionally streaked with 

 chestnut, the suture of the lower whorls with a white band ; interior red- 

 dish or yellowish-white ; peristome thickened ; apical whorls finely undu- 

 lately ribbed. Length 3-5 inches. Dentition, 55-1-55. 

 Var. a. — neozelanicus, Pfeiffer (1861). 



Shell ovately oblong ; peristome thinner. 

 Var. B. — candidus, Crosse (1864). 



Columella sub-vertical ; peristome very thick, white. 



North Island. — Cape Maria and North Cape (Dieffenbach, Gillies) ; Bay 

 of Islands (Captain Cook, Lesson, Colenso, Gillies, etc.). 



The animal has been described by Gould in the Zoology of the United 

 States Exploring Expedition. 



There has been some confusion in the name of this species. It appears 

 that Captain Cook brought specimens of Placostylus from New Caledonia 

 and New Zealand, and these were described by Bruguiere as B. bovinus, 

 from New Caledonia and New Holland. Martyn, about the same time, or 

 a year before, had described the New Caledonian species as B. fibratus ; and 

 Ferussac, Lesson, Petit, and Crosse have all decided that our shell should 

 be called bovinus. 



P. antipodabum, Gray (1843). 



Peristome thin. Shell pale fuscous variegated with dark lines, princi- 

 pally at the suture, where traces of a white band may also be often seen ; 

 apical whorls finely ribbed. Length 1 inch. 



The animal and dentition are unknown. 



