128 GASTROCOPTA, MASCARENE ISLANDS, ETC. 



close. I have been much inclined to think the Mascarene 

 forms imported, yet they occasionally develop a low crest 

 behind the lip, which I have never seen in G. servilis. In the 

 allied species this is a very variable character, of but slight 

 significance. 



The angulo-parietal lamella is like that of G. servilis, the 

 completely concrescent angular and parietal portions meeting 

 at a very wide angle directed towards the periphery, produc- 

 ing an emargination or somewhat bifid appearance in a front 

 view. This appearance is most marked in tripunctum, least 

 in seignaciana. 



Key to Species. 



a. Shell larger, from nearly 2 to over 2.5 mm. long. 



b. Angulo-parietal lamella distinctly bifid in a front 



view. G. tripiinctum, no. 75. 



6 1 . Angulo-parietal lamella emarginate in a front view. 



c. Teeth strong, the basal plica well developed. 



G. microscopica, no. 76. 



c 1 . Teeth weaker, basal plica typically minute or 

 wanting. G. seignaciana, no. 74. 



a 1 . Shell smaller, decidedly less than 2 mm. long. 



6. Rather slender, of 5 whorls. G. lienardiana, no. 77. 

 b\ Stouter, of 4% whorls. G. I. cudeli, no. 77a. 



74. GASTROCOPTA SEIGNACIANA (Crosse et Fischer). PI. 23, 

 figs. 1 to 4, 6. 



Shell rimate, small, of a lengthened subeylindric shape, 

 slightly striate obliquely, thin, subtranslucent, moderately 

 shining, of a corneous color. Spire relatively quite long, the 

 summit rather obtuse ; suture impressed. Whorls 5%, a little 

 convex, the last shortly rounded basally. Aperture vertical, 

 lunate-rounded, narrowed by two parietal teeth, one larger, 

 and of quite irregular form ; interior colored like the rest of 

 the shell. Peristome simple, corneous, the margins separated, 

 columellar margin reflected, basal margin rounded, reflected, 

 outer margin a little reflected, ascending, subangular near the 

 upper insertion, tapering, and ascending above the parietal 



