164 HELIX-LAB YRINTHUS. 



398. REEVE, Conch. Icon., f. 553. MARTENS, Binnenmoll. Ven- 

 ezuelas (Ges. Naturf. Fr. Berl., Festschr. 1873.), p. 12. Labyrinthus. 

 plicatvs SEMPER, Reisen in Arch. Philippinen, Land-mollusken, ii, 

 p. 105, t. 16, f. 9, (anatomy). H. labyrinthus var. ft Ferussac, 

 Histoire, t. 54B, f. 4. Carocolla labyrinthus (in part) LAMARCK, An. 

 s. Vert., iv, p. 96. REEVE, Conch. Syst., ii, t. 167, f. 3. Carocolla 

 hydiana LEA, Observations on the genus Unio, etc., ii, p. 98, t. 23, 

 f. 73, 73a. 



This species is about the size of H. labyrinthus, and like that 

 shell is often more or less pinched into an upward-flaring keel on the 

 last part of the whorl. The parietal tooth is shorter, less sinuous 

 and less deeply, entering than in H. labyrinthus, and the outer basal 

 tooth (which may be either squarish with crenulated tip, or conical) 

 is much smaller. The following measurements illustrate this differ- 

 ence ; the height of the tooth being taken from the outer edge of the 

 peristome directly to the tip of tooth. 



H. plicata. 



Diam. of shell 48, alt. of outer basal tooth 5 mill. 



Diam. of shell 37, alt. of outer basal tooth 4| mill. 

 H. labyrinthus. 



Diam. of shell 48, alt. of outer basal tooth 9 mill. 



Diam. of shell 37, alt. of outer basal tooth 6J mill. 



There is great variation in size in this species. The small denticle 

 inside the superior lip is frequently absent ; this is the case in the 

 specimen figured by Deshayes in Guerin's Magazin, 1838, pi. 110, 

 as the type of plicata. This specimen now lies before me. The 

 identity of this species cannot be questioned, as Born refers to 

 Knorr's Vergniigen, figure 5, pi. xxvi, (pt. v), undoubtedly 

 representing the true plicata. 



Variety. PI. 63, figs. 7, 8. 



This is a form with very thin light shell, the teeth rather slender 

 and long, sinus between the basal teeth very deep, as in H. labyrinthus; 

 whorls 4}, planulate, flatter than in H. plicata, and very acutely 

 keeled. Alt. 11, diam. maj. 30, min. 25 mill. 



Marmata, New Granada. 



H. UNCIGERA Petit. PL 42, figs. 23, 25, 25, 26. 



Umbilicate, depressed, lens-shaped, acutely carinated, deep chest- 

 nut or blackish-brown, with a broad whitish band above and one 



