APPENDIX. 383 



The spiral strise that cross its whorls are grouped in pairs ; 

 their interstices are raised, and more or less finely crenu- 

 lated; as they pass out on the expanded and •wing-Uke 

 varices they diverge, and the lobe-like projections that 

 scallop the margins of the wings are separated from each 

 other by each pair of diverging strise. The fine ribs that 

 cross the whorls are not present on the wings, nor on the 

 back ; they are nodulated at their decussation with the 

 raised strise. The wing-like varices of the whorls overlap 

 each other alternately on each side of the shell. The only 

 species to which it has affinity is the R. pulcJira. 



SCALAKIA JiTKESIANA. Tab. iii. fig. 7- 

 Testa lanceolato-turrita, gracUis, alba, Isevis, nitida, lon- 

 gitudiaaliter costata, costis lamellosis, reflexis, simplicibus, 

 nimierosis (in ult. anfrac. 20); anfractus 11, tumidi; 

 sutura profunde impressa; varices nuUi; apertura orbi- 

 cularis, margine Isevi. Long. 13, Diam. max. 14, apert 

 3 mill. (Mus. Brit.) 



This beautiful little Scalaria is deserving of particular 

 notice on account of the analogy and representation which 

 it exhibits with the ti. clathratulus of the seas of the 

 Northern Hemisphere. It is dedicated to the author of 

 the Voyage of the Fly. 



New Genus — Machilliveayia, Forbes. 



Shell spiral, dextral, globular, thin, corneous, transparent, 

 (in the only known species smooth or marked by obscure 

 lines of growth) imperforate ; spire not produced (with a 

 sinistral nucleus?). Aperture oblong, entire, angulated 

 below ; peristome incomplete, thin, even-edged. 



Operculum semicircular, horny, thin, composed of con- 

 centric layers with faint traces of a spiral structure at 

 the centro-lateral nucleus, which is on the columellar 



