PTEROC YCLOS. 



Plate IV. 



Species 17. (Mus. Cuming.) 



Pterocyclos biciliatcs. Pier, testa late aperli nni- 

 bilicatd, discoided, fulvd, caslaneo late undatd, an- 

 fractibus rotundalis, dense striatis, supra et infra 

 peripheriam seriatim ciliatis, a>ifniclu ultimo pone 

 operturam tuhulo recurvo munilo ; aperturd oblique 

 ctrculiiri, labro siiperne tenuejiexuoso-dihitaio. 



The two-lashed Pterocyclos. Sliell broadly openly 

 umbilicated, discoid, fulvous, broadly waved witii 

 chestnut, whorls rounded, densely striated, encircled 

 above and below the periphery with a row of lashes, 

 last whorl furnished behind tlie aperture with a re- 

 curved tube ; aperture obliquely circular, lip thinly 

 flexuously dilated at the upper part. 



MoussoN, Benson, Ann. Nat. Hist. ser. 2. vol. xv. p. 14, 

 Cyclosloma biciUatum, Pfeiffer. 

 Cyclostoma Ckarbouuieri, Eecluz. 

 Cyclotus Tai/lorianus, Pfeilfer. 

 Opislhoportts bicitiatus, Benson. 



Ilab. Sarawak, Borneo. 



The species represented in this and the followini;- plates, 

 characterized by the presence of a tubular process emerging 

 from behind the aperture, constitute the genera Opidho- 

 porus and Bhiostomu of Benson. When it is a little re- 

 moved from the aperture the species belong to the former 

 group, when arising from a tubular sinuation of the lip, to 

 the latter. ■ P. cilialus is distinguished as a species in 

 being encircled on either side of the jJeriphery, with a 

 neatly-delined row of bristlv lashes. 



Species 18. (Fig. a, b, Mus. Cuming.) 

 Pterocyclos eirostris. Pter. testd laiissime aperti 

 umbilicatd, discoided, fulvd, caslaneo fasciatd et acute 

 undato-strigatd, aufractibus rotundalis, uudique unuu- 

 lalo-striaUs, aiifractu ultimo subsolulo,poiie aperluraiu 

 tuhulo incuno muiiito ; aperturd circulari, labro 

 coneavo-injleclo, superiie tubulo-sinuato. 

 The two-beaked Pterocyclos. Shell very. broadly 

 openly umbilicated, discoid, fulvous, banded and 

 sharply wave-streaked with chestnut, whorls rounded, 

 ving-striated throughout, last whorl rather uncoiled, 

 furnished with an incurved tube behind the aperture ; 

 aperture circular, lip concavely intlected, tubularly 

 sinuated at the upper part. 

 Cyclotus birostri^, PfeiSer, Pro. Zool. Soc. 1854, p. 300. 



Opisthoporus birostris, Pfeiffer. 

 Hab. Sarawak, Borneo. 



The tube behind the aperture is not curved backwiu-ds, 

 as in the last species, but forwards, and a second tube is 

 formed by an inflected sinuation of the lip. 



Species 19. (Fig. a, b, Mus. Cuming.) 



Pterocyclos Haixesii. Pter. testd ampliter perspective 

 umbilicatd, subdiscoided, fulvescenle-fuscd, caslaneo 

 fasciatd et marmoratd, anfractibus ad sulurns subup- 

 pressis, delude rotundalis, dense striatis, anfraclu id- 

 tirno coHSpicue solulo ; aperturd circulari, labro crasse 

 rejlexo, superne tubulo recurvo prominente munilo. 



Haines' Pterocyclos. Shell largely pcrspeetively um- 

 bilicated, somewhat discoid, fulvous-brown, banded 

 and mottled with chestnut, whorls a little appressed 

 at the sutures, then rounded, densely striated, last 

 whorl conspicuously unrolled ; aperture circular, li|) 

 thickly reflected, furnished at the upper part with a 

 proniinoit recurved tube. 



Rhiostoma Hainesii, Pfeitter, MS. in Mus. Cuming. 



Hab. Cambojia ; !Mouhot. 



A very striking species, in which the last whorl is un- 

 coiled on arriving at maturity, to make room for a con- 

 spicuous recurved tube, emerging from the upper nuu-gni 

 of the aoerture. 



Species iO. (Fig. a, b, ilus. Cuming.) 



Pterocyclos simplicilabris. Pter. testd late aperte 

 umbilicatd, discoided, fulvd, rufo-fusco fasciatd et 

 uudulato-strigatd, anfractibus rotundalis, undique 

 dense anuulato-striatis, anfraclu ultimo solulo ; aper- 

 turd circulari, labro calloso- rejlexo, sinu in tubulum. 

 producto. 



The simple-lip Pterocyclos. Shell broadly umbdi- 

 cated, discoid, fulvous, banded and wave-stre.iked 

 with brown, whorls rounded, closely ring-striated 

 throughout, last whorl uncoiled; aperture circular, 

 lip callously reflected, sinus produced into a tube. 



Pfeifeer, MS. in Mus. Cumiu"- 



c 



Ilab. Cambojia. 



In this and the species which follows, the last whorl is 



February, 1863. 



