ACHATINA, WEST AFRICA. 25 



<?ollegit Georgius Tarns Med. Dr., p. 7, pi. 1, f. 39, 40 (1853). 

 PHILIPPI, Abbild., ii, p. 214, pi. 1, f. 2. PFR., Monogr., ii, 

 259; Conchyl. Cab., p. 334, pi. 29, f. 4, 5 (bad). REEVE, 

 C. Icon., v, pi. 1, f. 1. MORELET, Voy. Welwitsch, p. 71. 



Tliis is one of the narrowest species of Acliatina. It has 

 the general appearance of Limicolaria. The initial whorl 

 and a half are smooth ; then follow several very finely, densely 

 striate whorls, the striae cut into long granules by incised 

 spirals. This decussation usually disappears wholly from the 

 last whorl or two, but sometimes persists just below the 

 suture. The oblique stripes of the surface usually are 

 abruptly replaced on the last whorl by narrower vertical 

 streaks. Two specimens of the series before me measure: 



Length 36, diam. 14, apert. 15 mm., whorls 8y 2 . 



Length 42, diam. 14.5, apert. 14 mm., whorls 9. 



Dr. Welwitsch reports this agate snail as of frequent occur- 

 rence on the margins of the small lakes of Quicuje (Loanda), 

 where they bury themselves very deeply in the sand in the 

 dry season. Large ones attain a length of 48, breadth 10 

 mm., with 9 whorls. 



A. ivensi was described from one specimen, probably not 

 quite adult. It is evidently very closely related to A. pfeif- 

 feri, and I believe identical. It was collected by Capello 

 &nd Ivens, who explored in the Zambesi valley, but who 

 probably touched at Loanda on their voyage to or from Por- 

 tugal. No locality was given by them for the species. The 

 original description follows: 



A. ivensi Furtado. PI. 19, figs. 28, 29. Shell ovoid, elon- 

 gate, solid, glossy, ornamented with fine and close growth- 

 lines, and below the suture, spiral striae forming a fine de- 

 cussate-granulation. Whorls 8, convex, the summit relatively 

 quite large and obtuse; suture well marked, white, strongly 

 plicate and bordered. Coloration of oblique lines and flam- 

 mules of a dark chestnut color on a waxen-white, bluish or 

 yellowish ground; these lines being arrested on the face of 

 the last whorl by a sort of growth-arrest or varix, after 

 which the flames begin vertical, gradually becoming oblique 

 again. The stripes cover more and more of the surface, so 



