28 GASTEROPODA. PLEUROBRANCHID#: 
gate. Pes posticé rotundatus, integer. 
Testa subcalearea, tenuissima subreflexa. 11. Oscanrus. 
Branchize attached between the junction of the mantle and 
foot. Two labial tentacula, which are involute. Margins of 
the foot dilated. Mantle dilated on every side, covering the 
shell, which is found in all the indigenous genera, and is more 
or less calcareous. 
Pleurobranchus Peronii of Cuvier is the type of his genus 
Pleurobranchus, on which this family is founded. 
Genus 10. CLEANTUS. 
Os tubulosum. Labium crassum, supra ac infra lamella 
simplici instructum : lamella superior major ; inferior ex pedis 
reflexione efformata. Pallium integrum pede multo latius. 
Branchie elongate. Pes posticé angustior, integer. Testa 
calcarea, oblonga, patula. 
Mouth tubulose. Lip thick, furnished above and below with 
a simple lamella; the upper lamella largest ; the under one 
formed by a reflection of the foot. Mantle entire and much 
broader than the foot. Branchiez elongated. Foot narrower 
at its posterior extremity, and entire. Shell calcareous, oblong, 
spreading. 
1. CLeantus MontaGut. Plate VII. fig. 4—7. 
C. testa concentricé striata; striis antiquatis. 
Bulla Plumula, Mont. Test. Brit. 214. t. 15. fig.9; M. & R. 
Trans. Linn. Soc. vin. 123; Turt. Conch. Dict. 25. 
Animal flavicante-luteum, dorso vesiculoso. 
Habitat in Danmonie Australis littoribus, haud infrequens. 
Shell concentrically striated, the strize antiquated. Colour 
without, reddish or reddish-brown; pearly white or pearly 
within. Young shells are often pearly on their outside. The 
antiquated strie are very distinctly impressed on the mner 
surface. 
Length nearly half an inch ; sometimes, but very rarely, as 
large as the one figured in Pl. VII. ! 
Animal yellowish, inclining to luteous. Back vesiculose. 
