152 



deeply sinuated ; in age not so much thickened as in C. seminudus, 

 but in one instance of a larger (than typical) old shell, very tnuch 

 produced from tlie body-whorl. Umbilicus, narrow ; greatest breadth 

 0*3, least breadth 0*24. TJmhilical Aee/jWell developed, not very broad. 

 Ojierculum, planular above, Tvitb a sligbtly elevated, broad, rounded 

 lamina, of about 5 whorls far apart, and the lašt much farther from 

 the outer edge of the operculum ; the margins broadly reflected and 

 expanded on the plane of the operculum and covered with sharp 

 excentric strise ; on the under side, the centre is elevated at the 

 nucleus, then concave and broadly raised all round the edge ; greatest 

 breadth 0-43, least breadth 0-4. Height of shell 0-84, greatest 

 breadth 0*99, least breadth O "82. Named in compliment to Mrs. 

 De Burgh. 



I liave reason to fear that I may have distributed this shell as 

 C. seminudus. Let me here observe how excelleut a guide is the 

 operculum ; but for the concavity of C. seminudus and the flatness 

 of this, other diiferences might have escaped notice. How marked 

 are the differences, hovvever ! 



Measurements of Measurements of 



C. seminudus. DeBurghčsanus. 



Height of shell 0-65 084 



Greatest breadth 1 inch 0*99 



Least breadth 079 0-82 



Greatest breadth of umbilicus. . 0*41 0*3 



Least breadth 0-34 0-24 



Greatest breadth of operculum. . 0'34 0*43 



Least breadth 0-32 0-4 



C. RUDis-PLANusauE, Chitty. Accompong Town, St. Elizabeth. 



This shell, likevdse, Adams has distributed as a variety of C. varians, 

 from which it most materially differs in its operculum. It is, how- 

 ever, a puzzling shell, as it varies so much in its dimensions, as seen 

 below. 



Form, globose-conic. Colour, dark brown ; sometimes light red- 

 brown ; sometimes, in age, almost black on the lašt whorl ; some- 

 times with a light narrow band at the periphery ; sometimes with a 

 broad band. ScuJpture, inconstant, generally shining and smooth, 

 except for rather coarse strise of growth ; sometimes finely corru- 

 gated on the penult whorl and below the snture on the lašt whorl, 

 and below, at the junction of the peritreme and umbilical keel ; 

 sometimes merely slightly pitted here and there ; sometimes with 

 the lines of growth very coarsely developed on the upper whorls ; 

 coarse lines of growth within the umbilicus. Spire, well elevated, 

 with convex outlines. TFhorls, A^, moderately rounded, with deep 

 suture above ; moderate suture at the termination of the lašt whorl, 

 which is much depressed. Aperture, pyriform, expauded on the 

 right. Peritreme, generally very sinuate on the right above. Um- 

 bilicus, narrow, greatest breadth 0'25, least breadth 0-22. Umbilical 

 keel, weil developed. Operculum, likę C. DeBurgluBanus, only 

 planular on the under side. 



