506 



PROCEEDINGS OF THE ACADEMY OF 



[Aug., 



Pleurodonte (Labyrinthus) uncigera (Petit). Fig. l. 



Caracolla uncigera Petit, Mag. de Zool., 1838, pi. 113. 



Pleurodonte (Labyrinthus) tenaculum Dall, Smiths. Misc. Coll., Vol. 52, 

 part 3, p. 361, pi. 37, figs. 5, 6, 10, 11. 



This species is well distinguished by the hook within the basal lip, 

 projecting between two basal plicae, though really arising from the 

 inner part of the outer plica. Petit's very good figure of this struc- 

 ture is copied in my fig. 1. A whitish band revolves above, another 

 below the peripheral keel, which is dark. Diam. 27-30 mm. 



Isthmus of Panama (Pavagean, type of uncigera); near the Atrato 

 River, Sierra Darien (Heighway, type of tenaculum). 



Fig. 1. — P. uncigera (after Petit). 



Fig. 2. — P. u. chiriquensis. 



Pleurodonte (Labyrinthus) uncigera chiriquensis n. subsp. Fig. 2. 



Helix uncigera Pilsbrv, Manual of Conehology, V, p. 164, pi. 42, figs. 23, 25, 

 25, 26. Not of Petit. 



The shell resembles uncigera in shape and color, and in the form 

 of the aperture. There are two teeth within the basal lip, the inner 

 one small, tubercular, sometimes nearly obsolete; outer tooth entering 

 pliciform, double, consisting of an inner fold terminating in a hook 

 or vertical lamina, and an outer fold superposed upon the other, not 

 reaching so far forward. 



Alt. 12, diam. 27.5 mm. 

 " 12. " 28 

 " 12, " 30 



Chiriqui, Isthmus of Panama (McNeil exped.). Type No. 5612, 

 A. N. S. P. Also taken by Dr. W. Xewcomb on the Isthmus, exact 

 place not stated. 



In this form the hook does not stand free from the entering lamina, 

 as it does in uncigera. The lamina overrides the fold bearing the 

 hook, and does not continue to or upon the peristome. In several 



