1927] Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian Congo yee 
More of the mutans form occurred at this place than elsewhere. 
Lang’s label states that it is ‘common on the shore of the Congo 
River at low tide, both varieties together. At certain places one or the 
other predominates. July 4, 1915.” 
Malela, from another place, August, 1915. Several hundred speci- 
mens of the form fusca only, the size and other characteristics very 
uniform. An average specimen and the largest seen measure: 
Length, 19.5 mm.; diameter, 10.0 mm.; 5 whorls. 
oa a 11.0 Soo3 
The special ecologic features of the station of this pigmy form were 
not noted. ; 
Kunga. <A small series of medium size, about: length, 32 mm.; 
diameter, 15mm.; 4 whorls. Only the fusca form occurred. The carinate 
phase sets in early, and apparently consists of five or six whorls. It is 
therefore an extreme form of the fusca type. | 
San Antonio. The series of some hundreds of specimens is divided 
into living shells and dead ones containing hermit crabs. Barnacles 
are found on the shells of both lots. All of the shells taken alive are 
of the form fusca. All are small, about 218 to 9 mm., with about 7 
whorls, of which 2 to 3 are carinate. They taper to a very small apical 
truncation. Many specimens have two dark bands, as figured by Han- 
ley as matont Gray. (Pl. XXIII figs. 44a). 
The crab shells are larger, 25 to 32 mm. long, and include both 
fusca and granulosa forms, the latter rather finely ribbed. ‘There are 
also a few of the mutans blends. These were probably brought by the 
hermit crabs from the mangrove swamps, where similar specimens are 
known to occur. 
From the frequent presence of barnacles, the slight degree of ero- 
sion, and the absence of ferric incrustation, it may be presumed that the 
water in this place is decidedly salt, too saline for the optimum growth 
of the species. 
San Antonio, in a mangrove swamp occasionally submerged (PI. 
XXIV, figs. 5-5b). Several hundreds of specimens, of which many are of 
the form granulosa with numerous small axial ribs (Pl. XXIV, fig. 5). 
Others have the ribs more emphatic with prominent tubercles below the 
suture, like the stage immediately preceding the carinate stage in form 
fusca (Pl. XXIV, fig.5a). Some havea brief fusca stage with the upper 
carina either lobed or rarely even for a short space, then becoming lobed 
and more or less fully returning to the granulosa type (Pl. XXIV, fig. 5d), 
