18 NON-MARINE MOLLUSCS OF SURINAM. 
Pfeiffer, 1872, p. 76. Upper Surinam River. 
Martens, 1873, p. 218. Surinam. 
Kappler, 1887, p. 204. Surinam. 
Strebel, 1909, pp. 142, 144, 145. Surinam, Upper Maro- 
wijne, Para District. 
* 42. SIMPULOPSIS CORRUGATA Guppy. 
Simpulopsis corrugatus, Guppy, Ann. Mag. Nat. Hist. (3), 
Vol. XVII, 1866, p. 53. 
Simpulopsis corrugata Guppy, Pilsbry, Man. of Conch., 2. ser., 
Vol. XII, 1899, p. 217, Pl. 64, f. 93—95. 
Post Groningen. van Heurn, 1911. 
The single specimen, collected by Mr. van Heurn, is 
agreeing in every respect with the description given by 
Mr. Pilsbry. The occurrence of this species in Guyana is 
reducing very much the wide geographic separation, be- 
lieved to exist between S. corrugata (Trinidad) and S. rufo- 
virens Moric. (Province of Bahia, Brazil). Possibly Mr. Smith !) 
is right in uniting the two species. In that case Moricand’s 
name has the priority for the species; and corrugata may 
be the name for the Trinidad- and Guyana-variety. 
* 43. OPEAS GRACILE Hutt. 
Bulimus gracilis, Hutton, Journ. As. Soc. Bengal, Vol. III, 
1834, pp. 93, 85. 
Achatina subula, Pfeiffer, Arch. f. Naturgesch., 1839, p. 352. 
Opeas gracile Hutt., Pilsbry, Man. of Conch., 2. ser., Vol. 
XVIII, 1906, pp. 125, 198, Pl. 18, f. 3—6, Pl. 28, f.70. 
Environs of Paramaribo. van Heurn, 1911. 
This species, widely distributed in the West-Indies, 
Central-America and the north of South-America, was 
not yet recorded from the Guyana’s. 
* 44 OPEAS MICRA d’Orb. 
Helix micra, d'Orbigny, Mag. de Zool., 1835, p. 9. 
Opeas micra d’Orb., Pilsbry, Man. of Conch., 2. ser., Vol. 
XVIII, 1906, p. 193, Pl. 27, f. 49, 56, 57. 
Environs of Paramaribo. van Heurn, 1911. 
? Martens, 1873, p. 215. Surinam. 
1) Journ. of Conch., VIII, p. 244. 
Notes from the Leyden Museum, Vol. XXXVI. 
