54 BULlrETTN 181, UNTTED STATEI9 NATTONAlj MUSEITM 



Genus AMPHICYCLOTULUS Kobelt 



1912. Amphicyclotulus Kobelt, Martini-Chemnitz, Conchylien Cabinet, vol. 1, 

 sect. 19, pt. 3, p. 913. 



Small cyclophorids with chondroid multispiral operculum, the 

 outer edge of which is 7iot expanded into fimbriations. The spire is 

 marked by incremental lines and in the typical subgenus bears raised 

 spiral cords, at least on the early whorls. In this they may also be 

 present on the base. (In the subgenus Cycloblandia the spiral cords 

 are absent.) The base is broadly openly umbilicated. The peristome 

 is not thickened or reflected. 



Type: Amphicydotulus rvfescens (Sowerby). 



The genus is Antillean. 



The anatomy oi A. {A.) acutiliratus (Drouet) and A. {A.) mineri 

 shows the radula to have the formula 3:3:3:3, and the jaw without 

 median projection. The verge is on the back of the neck behind the 

 tentacles and is traversed by a vas deferens. The terminal appendage 

 is long and threadlike, almost as long as the basal portion. 



KEY TO THE SUBGENERA OF AMPHICYCLOTULUS 



Shell with spiral lamellae Amphicyclotulus 



Shell without spiral lamellae Cycloblandia 



Subgenus Amphicyclotulus Kobelt 



A7)ipMcyclotulus in which all or at least the early postnuclear whorls 

 are marked by raised spiral cords, which may or may not be present 

 on the base. 



Type: Am'phicylotultLs rufescens (Sowerby). 



This subgenus is known from Puerto Rico, Guadeloupe, Dominica, 

 and Martinique. 



KEY TO THE SPECIES OF SUBGENUS AMPHICYCLOTULUS » 



Spiral sculpture confined to early postnuclear whoi'ls. 



Shell orange-yellow mineri 



Shell was yellow guadeloupensis 



Spiral sculpture not confined to early postnuclear whorls. 

 Spiral sculpture consisting of strongly raised cords. 



Spiral cords on spire strongly crenulated rufescens 



Spiral cords on spire not strongly crenulated. 



Spiral cord bounding umbilicus stronger than the rest, acultiliratus 

 Spiral cord bounding umbilicus not stronger than the rest. 



Spiral cords of base distantly spaced schrammi 



Spiral cords of base not distantly spaced dominicensis 



Spiral sculpture not consisting of strongly raised cords. 

 Spiral sculpture consisting of strongly raised threads. 



Spiral threads numerous liratus 



Spiral threads few pei*plexus 



^A. (A.) portoricensis (Boettger) is not included in this key, as I have not seen speci- 

 mens of it. 



