42 University of Michigan 



H. Shell shaped like P. gigantea: blackish fuscous with 

 yellowish brown, peripheral stripe. Ecuador. 2^ ; 



165(38); 4'.^ 



....'V. (gigantcus xar?) siihcingulatus Kohert (1912). 



HH. Shell more elevated: olivaceo-castaneous, with light 

 stripe at periphery and darker band below. Colombia. 



29.5 : 144(42.6") ; 41^ 



Cyclostoma cingidatum Sowerby (1843). 



DD. Periphery of last whorl rounded. 



I. Shells very large; major diameter more than 45 mm. 



J. Last whorl descending, with upper angle canaliculate ; 

 dark band below peripheTA\ Vera Paz, Guatemala (?) 



35.1; 139(48.7) 



..(!) Apcrostoma confusum Sykes (1901) Jour. Malac. 



JJ. More depressed ; descent of last whorl less pronounced. 



K. Color rich chestnut-brown : lighter at suture and base, but no 

 spiral bands. Zaragoza, Colombia (L ", 75). 2i^\ 159(51); 5- 

 Ncocyclotus belli Beddome ( 1908) . 



KK. Dark, spiral band below lighter stripe at periphery. 



L. Slightly more elevated ; growth lines much coarser towards 

 umbilicus than on sutural side of last whorl. Ecuador. 

 Z2.2,\ 161(51.9); 5 Cyclotus fischeri Hidalgo (1867). 



LL. Most depressed ; growth lines not markedly coarser below. 



Near Panama Cit3^ Panama. 36; 166(59.8); 5' 2 



Cyclostoma gigaiiteum "Gray" Sowerby (1843). 



(-\-C. cumiugii Jay, 1850). 



II. Shells smaller; major diameter less than 40 mm. 



M. Much depressed, rapidly increasing whorls ; color brownish- 

 olive, with light stripe above periphery, bordered by dark 



brown above and below. Peru. 13; 212{2'J.^) \ 4 



Xeocyclotus depressus DaCosta ( 1906). 



MM. Less depressed ; not more than twice as broad as high. 



N. Color predominantly reddish ; usually distinctly larger and 

 heavier shells, with prominent growth lines, at least 

 around umbilicus. 



O. More depressed ; chestnut-brown above, dark-brown be- 

 low, with narrow, peripheral stripe of light color; 

 growth lines weak. Pozuzo, Eastern Peru. 20.4; 183 

 (38); 4!^ Ncocyclotus pcnivianus DaCosta (1906). 



