358 ' GASTROPODA. [Pectinibranchia. 



superficial, slightly uneven, margined above by a fine thread. Aper- 

 ture broadly ovate, almost round, suddenly narrowed into the canal, 

 which is much produced, narrow, quite straight, and of about the 

 same length as the spire. Outer Up sharp, slightly denticulated by 

 the spiral sculpture. Columella straight, smooth. Inner Up narrow, 

 thin, extending over the parietal wall and down into the canal. Oper- 

 culum unknown. 



Diameter, 22 mm. ; height, 73 mm. Angle of spire, 42. 



Animal unknown. 



Type in the British Museum. 



Hob. Cook Strait, near Kapiti Island ; off Great Barrier Island, 

 in 110 fathoms. 



Fossil in the Pliocene and Miocene. 



Genus 2. LATIRUS, Montfort, 1810. 



Latirus, Mtft., Conch. Syst., ii, 1810, 531. Type : Murex gibbulus, flmel. 

 Polygona, Schumacher, 1817. Plicatdla, Swainson, 1840. Eolatirus, 

 Bell, 1883. Plesiolatirus, Bell, 1883. Taron, Button, 1883. 



Animal having conical tentacles, the eyes at their outer bases ; 

 foot oval ; siphon short. Radula with the central tooth tricuspidate, 

 laterals with about 10 denticles, broader at the base, not so long as 

 in Fasciolaria. 



Shell turreted, fusiform, sometimes umbilicated ; spire produced ; 

 whorls nodulous ; aperture oval-oblong ; outer lip thin, crenulated ; 

 columella straight, with 2 or 3 small oblique plaits in front. Oper- 

 culum oval, elongated, unguiculate. concave at the columellar border ; 

 nucleus apical. 



The genus is represented in the Indian Ocean, the Philippines. 

 Australasia, Pacific Islands ; also in the West Indies. 



Fossil. It appears first in the Cretaceous, and is not uncommon 

 in the Tertiary. 



Button's genus Taron was founded on a supposed peculiarity of 

 the operculum of his Trophon dubius namely, that of being sub- 

 "concentric. This, however, is not correct, as the nucleus is distinctly 

 apical ; but the muscular scar is subcentral, near the columellar border. 

 The dentition of T. dubius is decidedly that of Latirus. (See also 

 Melvill, Mem. & Proc. Manchester Lit, & Philos. Soc. (4). iv, 12.) 



1. Latirus Huttoni, Suter, 1908. Plate 18, fig 2. 



Trophon dubius, Hutt., J. de Conch., xxvi, 1878, 13 ; T.N.Z.I., x, 293 : 

 M.N.Z.M., 49. Urosalpinx dubia, Hutt. : Tryon, Man. Conch. (1), 

 ii, 156. Taron dubius, Hutt., T.N.Z.I., xvi, 227 ; Plioc. M-, 40, pi. 6, 

 f. 10. Latirus Huttoni, Suter, T.N.Z.I., xl, 1907 (1908), 369, pi. 30, f. 3. 



Shell small, ovate-fusiform, solid, imperforate or with a light um- 

 bilical chink. Sculpture consisting of prominent narrow and rounded 

 spiral ribs, narrower than the interstices, 3 to 4 on the penultimate, 

 about 12 on the body-whorl, crossed by about 12 distinct broadly 



