ANOSTOMA. 113 



lower palatal folds well developed, the former a little larger and 

 more oblique ; suprapalatal fold tubercular, small or minute. 



Alt. 15, greater diam. 31, lesser 24 mill. 



Alt. 17^, greater diam. 34, lesser 25J mill. 



Brazil : Banks of the Amazon Rivev (E. Verreaux) ; " Rio del 

 Norte" (Coll. Acad. Nat. Sci.). 



Anostoma depressa LAM., An. s. Vert., vi, pt. 2, 101 (exclusive of 

 most references); Edit. Deshayes, viii, p. 152. Helix (Helicodonta) 

 ringens FERUSSAC, Histoire, pi. 53, f. 3-5. Anostoma verreauxianum 

 HUPE, Journ. de Conchyl. v (2d ser., vol. i), p. 352 (1851), and in 

 Castelnau, Exped., p. 22, pi. 3, f. S.-^PFR., Monogr. iv, p. 326 ; v, 

 p. 438. REEVE, Conch. Icon, xiv, pi. 1, f. 4a, 4b ? Helicodon 

 ringens SOWB., Catal. Shells Coll. Tankerville, p. 35 (1825). 



Distinguished from A. octodentatum chiefly by the narrower and 

 tinted lip, and fewer teeth. It is usually smaller, more angular at 

 the periphery, and less densely mottled beneath. 



Lamarck's original description of A. depressa is as follows: 

 " Shell suborbicular, convex on both sides, a little depressed, ob- 

 tusely carinated, imperforate, glabrous ; whitish with a circular 

 reddish line above ; aperture five toothed ; lip strongly reflexed." 

 He further remarks that it is sometimes spotted beneath, and has five 

 teeth, two on the columellar margin (parietal wall), and three on the 

 right lip. Greatest diam. 16 to 17 lines (=32 to 34 mill.). The 

 species has usually been placed under A. ringens of authors (A. octo- 

 dentatum F. de W.), as a synonym, but the size, number of teeth, 

 carina, etc., indicate that the shell Lamarck had was what Hup6 

 described later as A. verreauxianum. 



A. verreauxianum measures : alt. 15, greater diam. 30, lesser 23 

 mill., according to Hup. Neither Hupe nor Pfeiffer mention the 

 positions of the teeth of the outer lip, but Hupe"'s figures (pi. 6, figs. 

 53, 54) show that in the type, the columellar lamella and upper and 

 lower palatal folds are developed. Reeve figures a specimen (my 

 fig. 45) in which in addition to these, a suprapalatal appears, making 

 six teeth in all. 



In the specimens of A. depressum before me there is some varia- 

 tion, but all agree in wanting a columellar lamella. One of them 

 (pi. 6, figs. 50, 51, 52) labeled by Robert Swift as purchased from 

 Verreaux, and marked verreauxianum by the latter, has two parietal 

 lamellae, the parietal and the infraparietal, and upper and lower 



