410 GASTROPODA. [Pectinibranchia . 



below the shoulder. Suture impressed. Aperture ovate, slightly ob- 

 lique, produced below into a short, straight, and open canal. Outer 

 lip rounded, rather thick, crenulated and grooved ; adult specimens 

 toothed inside, the tooth near the canal larger than the others. Colu- 

 mella slightly oblique, straight, drawn out to a narrow ridge towards 

 the canal. Inner Up spreading but little beyond the pillar, extending 

 as a thin callosity over the concave parietal wall. Operculum with 

 the nucleus apical. 



Diameter, 10 mm. ; height, 17 mm. 



Animal unknown. 



Type in the Otago University Museum. Dunedin. 



Hob. Dunedin Harbour (type) ; Oamaru ; Cape Egmont (R. 

 Murdoch) ; Banks Peninsula (Iredale). 



Remark. Diagnosis drawn up from the type, kindly lent for the 

 purpose by Professor W. B. Benham. 



Subgen. 3. KALYDON, Hutton, 1881. 



Kalydon, Hutt., T.N.Z.I., xvi, 1883 (1884), 220. Type: K. corticatus, 

 Hutt. (= duodecimus, Hutt. ; not of Gray). 



Shell purplish or yellowish-brown, shortly fusiform, longitudinally 

 ribbed or undulated, and spirally striated. Operculum ovate, with 

 the nucleus subapical. Dentition as in Trophon. (Hutton.) 



In this subgenus the varices are replaced by axial ribs. Dr. H. 

 Strebel's group of Trophon decolor, Phil. (Zool. Jahrb., Syst., xxi, 

 209), seems to me to coincide with this subgenus. 



KEY TO SPECIES. 



A. Whorls convex, not distinctly shouldered ; with 10 strong 



rounded axial ribs . . . . . . . . . . convexus. 



B. Whorls distinctly shouldered. 



a. Without distinct axial ribs. Body -whorl with 3 nodulous 



keels and 4 spiral lirse on the base . . . . waipipicolft. 



aa. Axial ribs distinct. 



b. Number of axial ribs varying from 10 to 12. 



c. Protoconch smooth; axial ribs 11-12; penulti- 

 mate whorl with 4 cinguli . . . . aucklandicus. 



cc. Protoconch with spiral sculpture. 



d. With 12 broadly rounded axial ribs ; about 



6 spiral liree on the penultimate whorl . . corticatus. 

 dd. With 10-11, rarely 12, axial ribs; 2 spiral 



cords on the penultimate whorl . . curtus. 



bb. Number of axial ribs varying from 8 to 9. 



c. 9 axial ribs on body-whorl only, sometimes obso- 

 lete ; many spiral cords ; a strong not nodulous 

 keel at the shoulder . . . . . . inferus. 



cc. Penultimate whorl with 3, body-whorl with 9 



spiral cords . . . . . . . . erectus. 



ccc. 8-9 broadly rounded axial ribs, crispate growth - 

 lines, carina of shoulder nodulous ; many 

 spiral cords . . . . . . . . Paivce. 



bbb. Number of axial ribs about 18, reticulated by spiral 



cords, 3 (rarely 4 or 5) on the penultimate whorl . . plebejus. 



