Laoma.] GASTROPODA. 759 



rather stout callosity, expanded above, and sometimes partly hiding 

 the narrow perforation, but in young specimens it is always quite 

 open. 



Diameter Maj., 3mm. ; min., 2-5 mm. : height, 2-5 mm. 



Animal unknown. 



Type in my collection. 



Hob. North Island : Parua Bay, Whangarei, type (Musson) ; 

 Thames ; Waiwera (H. S.) ; Hunua Range (Major Broun). 



4. Group of Laoma sciadium. 



Umbilicus wide, one-fifth or more of the greatest diameter of the 

 shell, more or less perspective. 



KEY TO SPECIES. 



A. Shell with radial riblets. 



a. Suture margined, periphery acutely keeled . . . . sciadium. 



na. Suture simple, periphery convex or subangled. 



6. Riblets 10-15 per millimetre ; periphery convex ; 

 height of spire equal to that of the aperture ; di- 

 mensions, 1 mm. by 1 mm. . . . . . . lateumbilicata. 



bb. Riblets 8-10 per millimetre ; periphery convex ; 

 height of spire lower than the aperture ; dimen- 

 sions, If mm. by J mm. . . . . . . pumiln. 



bbb. Riblets 5 per millimetre ; periphery subangled ; 



dimensions, 2 mm. by 1 mm. . . . . raricostata. 



B. Shell without radial riblets, growth-lines only ; umbilicus 



perspective. 



a. Periphery obtusely carinated ; umbilicus nearly one-third 



of the diameter . . . . . . . . Titania. 



aa. Whorls sharply keeled ; umbilicus 45 per cent, of dia- 

 meter, carinated . . . . . . . . Murdochi. 



34. Laoma lateumbilicata, Suter, 1890. Plate 30, fig. 7. 



Hyalina allochroida, var. late umbilical a, Sut., T.N.Z.I., xxii, 1889 (1890), 

 228, pi. 15, f. 16, a, b. Laoma allochroida lateumbilicata, Sut., Man. 

 Conch. (2), viii, 64, pi. 23, f. 10-12. L. (Phrixgnathus) allochroida late- 

 umbilicata, Sut. : Hedley and Suter, P.L.S. N.S.W. (2), vii, 649 ; Suter, 

 J. de Conch., xli, 281. 



Shell minute, depressed globose, umbilicated, finely costate, thin, 

 pellucid, shining, horn-colour. Sculpture consisting of retractive ob- 

 lique riblets, 10 to 15 per millimetre ; interstices with microscopic 

 growth-lines, reticulated by rather indistinct spiral striae ; protoconch 

 devoid of sculpture. Colour yellowish-horny. Spire conoidal, convex, 

 its height the same as that of the aperture. Protoconch of 1| whorls, 

 rather large, broadly rounded. Whorls 5, regularly and slowly increas- 

 ing, narrow, rounded ; periphery and base convex. Suture impressed. 

 Aperture oblique, rotundly lunate. Peristome straight, acute, margins 

 converging. Columella short, vertical. Inner lip a little expanded 

 above. Umbilicus moderate, deep, open, about one-fifth of the 

 greatest diameter. 



