1927] Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian Congo 173 
records are from the Cunene River, Damaraland (Okosongoho), and 
northern Bechuanaland (Nausib River; Okovango; Lake Ngami; 
Botletle District), in the west; the mouth of the Zambezi in the east. 
A number of species occur in Madagascar, but the genus is unknown in 
the Mascarenes. 
In deference to the decision of the Intenational Commission on 
Nomenclature we are admitting Pila and a few other Bolten-Réding 
names. Itis hoped that this decision will be reversed. There seems little 
advantage to science in overthrowing nomenclature current for a 
century by the introduction of names from a sale catalogue of which 
only three or four copies were known to exist prior to the recent 
reprint. 
In Pila congoensis the respiratory siphon appears in the preserved 
specimens as a flat, subtriangular lobe adjacent to the left eye-pedicel, 
about 7 mm. long, 9 mm. wide at the base, in an individual with shell 
36 mm. long.! Inward, immediately adjacent to its base, is the large, 
oblong opening of the lung, which is 13 mm. long in the same specimen. 
This differs conspicuously from the condition found in Sumatran 
specimens of Pila ampullacea sumatrensis (Philippi) and in the American 
Pomacea paludosa Say (A. depressa Say), in which the opening of the 
lung is small, rounded, and near the middle of the pallial diaphragm or 
partition, thus well removed from the base of the siphon. 
The longitudinal ridge on the right side of the floor of the gill 
chamber is small. It unites anteriorly with the right or excurrent epi- 
podial lobe. The relations of these parts are shown in Fig. 140. 
In a Madagascar species identified as Pzla madagascariensis (Smith) 
the orifice of the lung is oblong, 10 mm. long, and situated rather nearer 
to the middle than to the right margin of the diaphragm. 
The penis of P. congoensis (Fig. 14a) is about 10 mm. long in an 
individual with shell 29 mm. long; situated on the right side of the 
mantle-margin near its termination. It consists of a slender cylindric 
organ, the penis proper, which is deeply furrowed by the spermatic 
groove throughout its length. There is a rather prominent tubercle, 
the hypobranchial gland, at its base. .It is enclosed in a fleshy sheath, 
1Annandale and Prashad (1921, Rec. Indian Mus., XXII, p. 9) describe the animal of the Indian 
Pila globosa (Swainson) as follows: ‘‘The right epipodial lobe is prominent and well developed. The 
inhalent siphon, which is formed by the left epipodial lobe, has, when contracted, the form of a promi- 
nent fold, forming part of a circle, but with its extremities widely separated. When expanded it is 
funnel-shaped and much broader than long.’”’ The gross anatomy of another Indian species, identified as 
Pila cinerea-(Reeve), has been recently studied by K.' Hagler (1923, ‘Anatomie von Pachylabra (Ampul- 
laria) cinerea Reeve, I. Teil.’ Acta Zoologica, IV, pp. 313-410). A more recent and detailed account 
of the anatomy of Pila globosa is that by B. Prashad (1925, ‘ Anatomy ofthecommon I ndian apple-snail, 
Pila globosa.’ Mem. Indian Mus., VIII, 3, pp. 91-152, Pls. xvi-xv1tt). See also K. Kagler, 1923, 
Anatomie von Pachylabra cinerea Reeve,’ Acta Zoologica, IV, 2-3, pp. 3138-394. 
