106 SYSTEMATIC ARRANGEMENT 



*** Operculum circular, of many whorls. Shell turrited, dextral. 

 Mouth subquadr angular, more or less channeled in front. Nape 

 not crested. Tentacles lateral ; veil none. 



■f Canal distinct, recurved. 



3. Bittium. 



Shell turrited ; whorls flattened ; aperture ovate ; canal moderate, 

 distinct. Operculum circular ; whorls rather large. — Adams, Gen. 

 Moll. t. 30. f. 3. 



1. B. reticulatum, t. 54. f. 5, t. 127. f. 4 ; Forbes fy Hanley, B. M. 



t. I.I. f. 2, t. O.O. f. 3 (operculum) ; Adams, Gen. Moll. 

 t. 30. f. 3. 



2. B. diemenense, t. 55. f. 13. 



The mantle of Bittium reticulatum is plain, forming a small 

 anterior dilatation to correspond with the shell, not a regular siphon. 

 Muzzle elongate, cloTen vertically. Jaws and lingual riband distinct. 

 Tentacles short. Eyes external, sub-basal. Foot rather short, trun- 

 cated; operculigerous lobe elongated, narrow before, broader be- 

 hind. Operculum subcircular, few-whorled. — Clark. 



Dr. Loven describes the operculigerous lobe of Bittium reticula- 

 tum as rather winged on each side, the hinder beard lanceolate, and 

 asks if it is a Rissoa (Moll. Scand. 23). Mr. Clark, adopting the 

 idea, considers it an elongated, turrited Rissoa. 



Teeth of Bittium reticulatum 3 • 1 ■ 3 ; the central subquadran- 

 gular, transverse (that is, rather broader than high), apex recurved, 

 denticulated ; lateral inner tooth rather broad, inner edge recurved, 

 denticulated ; outer tooth linear, bent rather like an f; the front of 

 the apex (or upper third) denticulated. Operculum spiral, subcircu- 

 lar ; whorls four, rapidly enlarging. 



4. Tympanotomus. 



Shell turrited ; whorls flat, tubercular ; mouth roundish ; canal 

 very short, curved ; pillar tortuous ; outer lip sinuated, produced in 

 front. 

 1. T. fuscatus, t. 53. f. 3. 



5. Telescopium. 



Shell conical, turrited ; whorls flat, last angular in front ; mouth 

 nearly four-sided; pillar twisted; canal short, curved; outer Up 

 dilated, sinuous. — Adams, Gen. Moll. t. 31. f. 1. 



1. T. fuscum, t. 54. f. 2, t. 127. f. 5, t. 267. f. 1. 



Lingual membrane of Telescopium fuscum tender. Teeth 3 • 1 • 3 ; 

 central small, recurved (denticulated ?) ; inner lateral broader, with 

 a slightly recurved apex to the inner broader end ; two outer lateral 

 subulate, arched, incurved. 



