﻿SNAIL HOST OF ORIENTAL LUNG FLUKE — ABBOTT 73 



brown color spots. The operculum is about two-thirds the size of the 

 aperture, opaque, and colored a dark blackish brown. The animal 

 and operculum may be withdrawn into the shell completely from 

 view. When fully extended the head and foot are, together, about 

 one-fourth the length of the shell. The foot is relatively small and 

 square to oblong. The proboscis is rather large and flattened. The 

 two tentacles are round and slender and extend slightly beyond the 

 anterior limits of the proboscis. Tlie mantle, which lines the interior 

 of the last shell whorl, is bordered by several prominent, fleshy 

 papillae, which may be seen projecting beyond the shell lip on the 

 left (or outer lip) side. In mature and gravid specimens a brood 

 pouch is present on the back of the animal just behind the head. In 

 some individuals the shells of the small, living young may be seen 

 through the thin dorsal wall of the pouch. 



EXTERNAL ANATOMY 



Shell (pi. 8, figs. 1, 2) : Many minor geographical variations 

 occur in the shell characters of this species, and since some confusion 

 is apt to result if a composite description of the various races is 

 presented, I have limited my remarks to a single colony, which was 

 collected on October 8, 1945, near the reservoir dam, Geus River, Guam 

 Island, Marianas (U.S.N.M. No. 590182). Supplementary remarks 

 are appended concerning the shell differences between the Guam 

 colonies and the population samples from Lithia Spring, Fla. 



Shell elongate-turrite, from 15.0 to 25.0 mm. in length, relatively 

 thin but strong. Color yellowish brown. From 7 to 11 whorls. First 

 3 or 4 whorls reddish brown with microscopic raised spiral threads and 

 rather stronger, retractively slanting, axial riblets, which increase in 

 strength on the succeeding whorls. Periphery of whorls nearly flat, 

 but becoming slightly more rounded in last whorls of specimens over 

 20.0 mm. in length. Spire pointed and cast at an angle of from 31** 

 to 35°. Suture well impressed, slightly irregular. Base of body 

 whorl very slightly rounded and cast approximately 35° from the 

 axis of the shell. Spiral sculpturing consists of 4 to 6, though most 

 commonly 5, rows of round to squarish, small beads. In later whorls 

 the lower 3 or 4 rows of beads become flattened and often fuse to form 

 a single raised, smooth spiral band. Beads of top row have a tendency 

 to become more pointed and tuberculate. Last whorl, including base 

 of shell, bears 12 to 14 spiral rows, although the lower 10 are nearly 

 always simple, raised bands without beads. Sharply incised, fine, 

 spiral lines may be developed on any of the whorls and, when occur- 

 ring on the tops of the beads, may in the following whorls become 

 deeper and wider, and finally spread apart what was originally one 

 row of beads into 2, 3, or rarely 4 rows. These incised lines occasion- 



