548 Transactions. 



being larger than the others. There are smaller riblets in the interstices, 

 including those on the siphonal groove and a wide space between it and the 

 next posterior large rib. Colour : Above bluish-grey, the ribs nearly white. 

 Apex corroded. Interior bluish-brown, the margin darker, and with nume- 

 rous white cross-bands opposite the ribs. 



Length, 17*3 mm. Breadth behind siphonal groove, 13-2 mm. Height, 

 5 mm. 



The type specimen of this subspecies differs considerably from that of 

 the typical subspecies, but intermediate forms which might be referable to 

 eir.Der are common, so that I could not divide them satisfactorily into two 

 groups, hence the present arrangement under one species. S. cheesemani 

 also in some of its forms approaches the subspecies perplexa. 



Habitat. — Living on rocks near low- water mark, Sunday Island. 



Siphonaria amphibia n. sp. Fig. 44. 



Description of Type Specimen. — Shell small, ovate, narrowed in front, 

 conoidal, height 0*35 of length. Apex behind the centre, anterior slope 

 slightly curved, posterior slope straight. Margin irregular, siphonal groove 

 slightly projecting. Sculpture : The upper half of the shell corroded. 

 Margin with about 25 scarcely raised radiating ribs. Colour brown, the 

 ribs white. Interior black, the margin crossed by white bands opposite 

 the ribs. 



Length, 7-8 mm. Breadth, 6*2 mm. Height, 2-7 mm. 



Variations jrom Type. — Most of the shells have the interior entirely 

 black, and in many the entire upper surface is corroded. 



Habitat. — This little species was found living in crevices and irregu- 

 larities of rocks near high-water mark at Fleetwood Bluff, Sunday Island. 

 In size, appearance, and habits it resembles some small species of Acmaea 

 which occur in similar situations in New Zealand. 



Gadinia conica Angas. 



Gadinia conica Angas, Pro. Zool. Soc, 1867, 115, 1868. 

 Recorded, Iredale, Pro. Mai. Soc, ix, 71, 1910. 



Habitat. — Living on rocks between tide-marks, Sunday Island. 

 Distribution. — New Zealand, Australia. 



Helicarion kermadecensis (Smith). 



Vitrina kermadecensis E. A. Smith, Ann. Mag. Nat. Hist. (4), xi, 288, 



1873. 

 Recorded, E. A. Smith, I.e. 



Habitat. — Living on the under-surfaces of the leaves of the nikau palm 

 (Rhopalostylis Baueri) on the summit of Moumoukai, the highest point of 

 Sunday Island. Found only during wet weather, October. 1908. Also 

 found living under dead leaves on the ground. 



Ptychodon royanus Iredale. 



Ptychodon royanus Iredale, Pro. Mai. Soc, x, 377, 1913. 

 Recorded, Iredale, I.e. 



Habitat. — Living on the moss-covered trunks of trees, Sunday Island. 



