176 GASTROPODA. [Aspidobrancliin . 



slightly exceeding one-third of the height of the shell ; base convex. 

 Suture impressed. Aperture a little oblique, subcircular. Peristome 

 simple, straight. Columella slightly concave, white. Inner lip spread- 

 ing over the umbilicus, sealing it up more or less completely. The 

 callus on the penultimate whorl unites the margins, and is con- 

 spicuous. 



Diameter, 1 mm. ; height, 2 mm. 



Dentition. Suter, T.N.Z.I., xxiv, 301, pi. 23, f. 58. 



Type in the K.K. Hofmuseum, Vienna. 



Hob. North Island : Bay of Islands (Purchas, Hochstetter) 

 Waro ; Whangarei ; vicinity of Auckland ; Wairangi, Waikato 

 Hunua Range ; Mount Pirongia ; Forty-mile Bush. South Island 

 Kenepuru Sound ; Nelson ; Wairoa Gorge ; Greymouth ; Riccarton 

 Bush, near Christchurch. 



Found in native bush in very moist situations, near creeks or 

 swamps, under stones, rotten wood, &c. 



ORDER 2. PECTINIBRANCHIA. 



(= Monotoccirdes ; Ctenobrcnichia.) 



These are Streptoneura with a somewhat concentrated nervous 

 system ; without a labial commissure, except in Vivipara and Ai- 

 puttaria. The nerve-collar is situated behind the buccal bulb, except 

 in the latter genus. There is a single well-differentiated, independent, 

 and often pectinated osphradium. The eye is always closed, and the 

 internal cornea (pellucida) is extensive. Each otocyst contains a 

 single otolith, except in some forms of Tcenioqlossa devoid of a pro- 

 boscis. The central tooth of the radula is single or absent. There 

 is no longer any trace of bilateral symmetry in the circulatory, re- 

 spiratory, and excretory organs, the topographically right half of the 

 pallial complex having completely disappeared. The ctenidium is 

 monopectinate, and attached to the mantle throughout its whole 

 length, except in Adeorbis and Valvata. The single kidney usually 

 opens directly by a slit-shaped aperture, and never serves for the 

 passage of the sexual products. The genital gland always has a sepa- 

 rate orifice of its own. The male generally has an intromittant organ. 



The Pcctinibmnchia are divided into two suborders Tcenioglossa 

 and Stenoglossa. 



SUBORDER 1. T^NIOGLOSSA, Troschel. 



In these Pectinibranchs the radula has nonnally 3 teeth on each 

 side of the median tooth viz., 1 lateral and 2 marginals. The 

 stomatogastric ganglia are situated behind the buccal mass, and are 

 united to the cerebral centres by long connectives, which are in part re- 

 current and deeply situated. The salivary ducts, when sufficiently long, 



