Latirus.] GASTROPODA. 359 



rounded axial costse, usually marked by nodules only on the last half 

 of the body-whorl ; growth-lines straight, fine and distinct, slightly 

 lamellar. Colour dark reddish-brown, flesh-colour around the canal ; 

 aperture dark purple inside ; columella white. Epidermis persistent, 

 greenish-brown. Spire sharply conical, a little higher than the aper- 

 ture ; outlines straight. Protoconch small, globular, axially costate. 

 Whorls 6, first slowly then rather rapidly increasing, distinctly narrowly 

 shouldered, convex below ; base contracted. Suture lightly impressed. 

 Aperture vertical, oval, narrowly canaliculate above, produced below 

 into a short slightly oblique open canal, rounded below. Outer lip 

 convex, sharp, slightly thickened and denticulate inside, but sometimes 

 smooth. Columella' vertical, almost straight, either smooth or with 

 a distinct tubercle below and one or two much smaller ones above it. 

 Inner lip narrow and thin, spread over the parietal wall, which bears a 

 distinct plait close to the outer lip, and descending, narrowed to a 

 long point, to the base of the canal, sometimes leaving there a slight 

 umbilical chink. Operculum corneous, 

 with apical nucleus. 



Diameter, 10-5 mm. ; height, 18 mm. 



(type)-. 



A nimal of a bright salmon-red colour. 



Dentition. Hutton, T.N.Z.I., xv, 119, 

 pi. 13, f. E. TEETH OP RADULA'. 



Type in the Otago Museum, Dunedin. 



Hob. Auckland Harbour, between tide-marks in rocky places ; 

 East Cape ; Bay of Islands. 



Fossil in the Pliocene. 



Fam. MITRIDj<E, Adams. 



Animal having a small narrow head ; tentacles close together at 

 the base, elongated, bearing the eyes at their sides ; proboscis very 

 long, cylindrical, flexible ; siphon moderately long, simple at the 

 base ; foot small, triangular, usually truncate in front. Purple gland 

 well developed ; verge narrow. The dentition presents several dis- 

 tinct types. 



Shell fusiform and solid, the spire pointed, the aperture elongated, 

 and the columella folded ; mostly destitute of epidermis, which is 

 very thin, smooth, and translucent when present. Operculum absent 

 or rudimentary. 



The Mitridce are abundant in the coral seas, and usually in a 

 moderate depth ; small species are subtropical, and some are found in 

 colder latitudes. 



KEY TO GENERA. 



A. Shell fusiform, thick ; aperture without a canal, notched at the 



base ; columella with 4 or 5 plaits ; outer lip smooth inside MITKA. 



B. Shell elongated, turreted, axially plicately ribbed ; aperture with 



a more or less recurved canal ; columella with 3 or 4 plaits ; 



outer lip internally striate . . . . . . . . VKXILLTTM. 



