316 Transactions. — Geology. 



a whorl. Suture well marked. No posterior band on the whorls. Aperture 

 ovate ; the columella twisted, produced into a short nearly straight canal. 

 No posterior sinus. 



Length, -53 inch ; breadth -15 inch. 



Locality. Wanganui. 



Distinguished from T. tristis by the stronger and smaller number of the 

 longitudinal ribs. 



Clathurella hamiltoni. PI. xviii., fig. 7. 



Shell ovato-fusiform. Whorls 7-8, rather shouldered behind ; the first 

 2^ embryonic, smooth ; the others strongly longitudinally ribbed and 

 crossed with fine spiral lirse. There are about 12-15 rounded, longitudinal 

 ribs in a whorl, and the spiral lirsB are small and close set. Aperture ovate, 

 rather angled behind ; posterior sinus obsolete ; the anterior end deeply 

 notched ; inner lip reflected over the columella. 



Length, -65 inch ; breadth, -33 inch. Length of aperture, "25 inch. 



Locality. Petane. A small variety is also found at Wanganui. 

 Clathurella dictyota. PI. xviii., fig. 8. 



Shell minute, elongato-fusiform. Whorls 6, the first two embryonic ; 

 the others slightly angled and cancellated. Longitudinal ribs narrow and 

 distant, about eleven in a whorl. Spire whorls with three strong distant 

 spiral ribs, the interstices finely spirally striated ; body whorl with about 9 

 spiral ribs, the posterior three larger, and alternating with a small rib 

 between each, as well as the spiral stride. Aperture oval, nearly half the 

 length of the shell ; posterior sinus broad and shallow ; anterior canal 

 moderate. 



Length, "23 inch ; breadth, -1 inch. Aperture, '11 inch. 



Locality. Wanganui and Petane. 



This species approaches C. oxyclathrus, Martens, but the spiral ribs are 

 fewer and further apart. 



Clathurella abnormis. 



Shell minute, mitriform, the spire produced and acute. Whorls 6^, the 

 first 1^ embryonic, polished ; the others angled, strongly longitudinally 

 costate and delicately spirally lined. There are eleven longitudinal ribs on 

 a whorl, which are crossed by three or four spiral threads in front of the 

 angle, none behind it. On the body whorl, the spiral threads in front of 

 the angle are about 12, some of which are stronger than others. Aperture 

 linear ; the right lip rather thick but not grooved ; a posterior shallow sinus 

 above the angle ; columella smooth. 



Length, "2 inch ; breadth, -08 inch. Aperture, *09 inch. 



Locality. Petane. 



