HOMORUS, WEST AFRICA. 153 



West Africa : Guinea. 



Achatina bacilliformis JON., Zeitschr. f. Mai. 1846, p. 13; 

 and in Philippi, Abbild. etc. ii, p. 215, pi. 1, f. 8. PFR., 

 Monogr. ii, p. 264; iv, 611. 



Described from a specimen with the apex broken off. 

 Pfeiffer remarks: "The shell, like many land shells from 

 Guinea, is very delicate, fragile and with a silken luster, very 

 finely and delicately striate, the whorls rather flat, the last 

 one short; the columella is pretty well-curved and strongly 

 truncate. ' ' 



The spire seems more straightly conic than in involuta and 

 its immediate allies. 



32. H. DECOLLATUS (Morelet) . PI. 59, figs. 63, 64. 



Shell decollate, thin, cylindric-turrited, greenish-corneous, 

 pellucid, glossy, marked with obsolete, irregular oblique 

 streaks. Suture minutely denticulate in the early whorls of 

 entire shells, in the rest submarginate. The 5% whorls re- 

 maining are rather flattened, slightly contabulate, the last ob- 

 tusely angulate at the periphery, two-sevenths the total length. 

 Columella arcuate, obliquely truncate. Aperture moderate, 

 acutely oval, the margins simple and unexpanded. Length 

 30, diani. 9 mm. (Morel.). 



West Africa: Gabun (Marche and de Compiegne). 



Achatina (Stenogyra) decollata MORELET, Journ. de 

 Conchyl. 1873, p. 330. PFR., Monogr. viii, p. 286. Steno- 

 gyra invalida MOREL., J. de C. 1885, p. 23, pi. 2, f. 15, a. b. 



This species was named decollata on account of its re- 

 semblance to Rumina decollata. The two shells at adult 

 age are truncated at the same height, ordinarily leaving 4 

 whorls. In the Gabun species the spire begins to be truncate 

 when the shell attains a length of 13 mm. The partition 

 which stops the breach is analogous in the two species. 

 Morelet subsequently changed the name of this species to pre- 

 vent confusion with the European R. decollata L. ; but no 

 change was necessary. 



33. H. PYRAMIDELLA Martens. 



Shell conic-turrite, lightly striatulate, glossy ; gray- whitish, 



