APPENDIX. G21) 



Vol. i. p. 412. Genus TROCHUS. 



Sub-gen. eochia, Gray. 



Shell with a strong fold on the pillar-lip, and a deep sinus 

 behind, near the whorl. T. acutangulus is au example. 



Vol. i. p. 414. Genus POLYDONTA. 



Sub-gen. precia, Gray. 



Shell, with the pillar-lip twisted, simple; axial cavity deep, 

 narrow, with a distinct, narrow, central, spiral rib. P. elegan- 

 tula is an example. 



Sub-gen. anthora, Gray. 

 Shell with the pillar-lip twisted, simple ; axial cavity moderate, 

 narrow, with several opaque, sub-spiral ridges. P. tuberculata 

 is an example. 



Vol. i. p. 484. Genus vitrinella. 



According to Dr. Gray, certain of the smaller species of 

 Cyclostrema. included by Brown in his genus Delphionoidea, are 

 Vitrinella}. The name Delphionoidea, however, it would be 

 more correct to add as a synonym of Skenea, and to transfer the 

 species of Cyclostrema in question to the genus Vitrinella, 

 which will then include the following species in addition to 

 those already given, excepting minuta, which is a Teinostoma, 

 and megastoma, semistriata, and striata, which are species of 

 Ethalia. 



costulata, Mull. nitidissima, C. B. Adams. 



elegantula, Phil. rota, Forbes and Hanley. 



lsevis, Phil. serpuloides, Mont. 

 nitens, Phil. 



Genus valvatella, Gray. 



(Sub-fam. trochin^.) 



Operculum circular, horny, many-whorled. 

 VOL. II. 4 M 



