78 GASTROPODA. [Aspidobranchia. 



and the branchial papillae are elongated conical, transversely foliated ; 

 larger black lamellae are placed at regular intervals, leaving 2 or 3 

 white papillae between them, and they have their base of insertion 

 higher up, on the inner side of the mantle. 



Type in the U.S. National Museum, Washington. 



Hob. Antipodes Islands, Auckland Islands (type), Campbell Island, 

 and Macquarie Island. 



Remarks. In specimens from the Auckland Islands the radiate 

 ribs are sometimes quite obsolete. Very often this species shows a 

 certain likeness with Helcioniscus strigilis by having the inside rayed 

 with dark brown and yellow, but it may be separated by the presence 

 of the metallic lustre. 



Genus 2. HELCIONISCUS, Dall, 1871. 



Helcioniscus, Dall, Amer. Journ. Conch., vi, 1871, 227. Type : Patella 

 variegata, Reeve. Helcioniscus, Thiele, in Trosohel's " Gebiss der 

 Schnecken," ii. 333 (full discussion and figures of the dentition) ; Man. 

 Conch. (1), xiii, 80, 123, 172. Cellana, H. Adams, P.Z.S.. 1869, 274 ; 

 type, Nacella cernica, H, Ad. 



The gill-cordon is interrupted in front, and there are no epipodial 

 processes or ridge on the sides of the foot. The formula of teeth is 

 3 (I 111 !) 3. The radula is long and spirally rolled. The central 

 tooth is narrow, with a variously shaped forward appendage. The 

 inner lateral has typically an outward wing, and a simple long cusp ; 

 the outer lateral has an inner long point with an outer side cusp, 

 besides a short mostly rounded longitudinal cutting-edge. The 

 marginal teeth are characteristic, the posterior part being divided 

 from the anterior, the connection thin and almost imperceptible. The 

 inner marginal tooth has a cusp on its front end. 



The shell is conical, the apex subcentral or subanterior ; inside 

 with a silvery and mica-like lustre. 



Distribution. Indian and Pacific Oceans, but not found on the 

 American shores north of Chili. No species have been found in the 

 Atlantic Ocean. 



KEY TO SPECIES. 

 A. Ribs almost smooth. 



a. 2025 separated narrow principal ribs, with 1 or more 



interstitial riblets, cut up into fine granules in front 

 of apex ; with divaiicating white or reddish-brown 

 blotches, or uniformly yellow, olive, or grey ; apex 

 anterior . . . . . . . . . . radians. 



b. Shell usually large, obliquely conical. 20-30 low distant 



ribs ; colour brown ; apex at anterior third to eighth ; 

 interior blackish-ptirple or light brown, with dark- 

 brown rays . . . . . . . . . . strigilis. 



c. Shell depressed to conoidal, ribs 20-30, brown, interstices 



often bluish-white ; apex anterior . . . . redimiculum. 



