184 BULLETIN 192, UNITED STATES NATIONAL MUSEUM 



and San Salvador. However, the greatest amount of material was ob- 

 tained during the investigation of the moUuscan fauna of the islands 

 of the Great Bahama Banks and the region to the south to Great Inagua 

 in 193 1, while the author was working under a grant of the Walter 

 Rathbone Bacon Traveling Scholarship of the Smithsonian Institution. 

 During this cruise we collected on every island of the Cay Sal Atoll 

 and on every island forming the chain of cays ranging from Flamingo 

 Cay southward to Great Ragged Island. We next visited the atoll formed 

 by Castle Island, Aklin Island, Crooked Island, and the Fish Cays, 

 making many stations on the larger islands. Next the upper Plana Island 

 was examined, but we were unable to land on the coral-bound southern 

 Plana Island on account of heavy weather, which made the reef-bound 

 cay inaccessible. Our next stop was on Mariguana Island, which was 

 thoroughly explored, as was also Booby Cay to the south of it. The 

 Caicos Atoll was next visited, and the ring of islands bounding it were 

 examined one by one, as well as those in the interior of the lagoon. Next 

 the cays of the Turks Island group were subjected to an overhauling. 

 Then Little and Great Inagua yielded a host of molluscan treasures 

 from many stations. 



Family ANNULARIIDAE Henderson and Bartsch 



1920. Annulariidae Henderson and Bartsch, Proc. U. S. Nat. Mus., vol. 58, 

 pp. 54-55. 



This family includes all the New World "cyclostomoid" moUusks 

 placed under the family name of Cyclostomatidae, Ericiidae, or Pomatia- 

 sidae. 



The chief distinguishing character that separates this group from all 

 other operculate pulmonates is found in the radula, which possesses a 

 unicuspid rachidian tooth, a single unicuspid lateral tooth, and two 

 marginals — an inner one resembling in form the lateral tooth, but multi- 

 cuspid, and an outer one, long and curved like a bow and pectinated 

 both upon its recurved edge and upon its main portion but not thereby 

 separated by the pectinations into a group of individual teeth. In a 

 very few exceptions a mere indication of an additional minute denticle 

 is apparent on the rachidian and lateral tooth. There is no jaw. The sole 

 of the foot is longitudinally divided by a sulcus, which separates it into 

 two muscular masses functioning independently from each other, thus 

 giving to the animal a method of progression by alternate waves of 

 muscular contraction, first on one side and then on the other. The foot 

 is relatively short. A bifid muzzle of varying length is always present. 

 The tentacles are long, slender, and fibrillar or slightly swollen at the 

 ends. The eyes are placed at the base of the tentacles on the outer side 

 and are often raised above the surface of the head by a fleshy protuber- 

 ance. 



The operculum shows a wide degree of variation through the various 



