164 OBSERVATIONS ON THE CHAROPID^, 



Desor"-— P.Z.S. 1867, p. 723; Men. Aust. L. Shells, p. 15; 

 Monographia Heliceorum Viventium, vii. p. 138; Man. Conch. 

 (2), ii. p. 209; Trans. N.Z. Inst, xxiii. (1890), p. 85. 



Shell thin, transparent ; contour sublenticular, apex obtuse. 

 Colour hyaline-white, painted above and below with very faint 

 radiating chestnut flames, each extending over three costse and 

 narrower than the colour interspace, about 17 of these ornament 

 the last whorl. Whorls 4^, gradually increasing in diameter, 

 upper whorls deeply channelled at their superior suture, somewhat 

 flattened below and descending tumidly to the inferior suture, last 

 whorl not descending at the aperture, channelled at the suture, 

 flattened between the suture and the periphery, rounded abruptly 

 at the periphery and gently on the base. Sculpture : the 

 embryonic surface is modelled upon that of the adult and consists 

 of faint capillary costse, which become sharper and stouter as the 

 growth proceeds, on the completion of a whorl and a-half the 

 adult sculpture is abruptly substituted for the embryonic ; the 

 costse here suddenly change to four times the size of their prede- 

 cessors, with corresponding increase of the width of their interstices, 

 in proportion as the shell increases so the intercostal spaces widen, 

 their width is not always uniform nor are the costse always of 

 uniform size, more rarely they are not parallel, never do they 

 continue across the suture from whorl to whorl, on starting from 

 the suture the latest costse are seen as sharp erect lamellae directed 

 square across the whorl, nearing the periphery they ti-end obliquely 

 backwards, their upright crest curling backwards, arrived beneath 

 the periphery they steer straight across the base to the rim of the 

 umbilical crater, into which they plunge directly, viewed edgeways 

 (the apex of the shell uppermost) each costa is somewhat the shape 

 of a letter S whose upper bend has been straightened ; upon the 

 last whorl I counted 83 and upon the penultimate 60 costse ; 

 between and parallel to the costse are from four to twelve micro- 

 scopic raised hair-lines, which are crossed at right angles by similar 

 spiial lines ; this secondary sculpture, which also extends over the 

 costie, gives an appearance of network to the shell when highly 

 magnified, here and there a hair-line thickens into a rudimentary 



