HELIX-LABYRINTHUS. 161 



H. LABYRIXTHUS (Chemnitz) Desh. PL 39, figs. 87, 88, 89, 90 ; pi. 

 64, figs. 14-16. 



Umbilicate, depressed, about equally convex above and beneath, 

 acutely keeled at the circumference ; strong and solid but not thick, 

 rich chestnut-brown in color ; surface shining, lightly obliquely 

 striate, under a lens very minutely granulate ; spire convex, low, 

 apex planulate, smooth, whitish ; suture scarcely at all impressed ; 

 whorls 5, nearly flat, regularly and gradually widening, the last de- 

 pressed, acutely cariuated at the periphery, deflexed anteriorly ; the 

 keel on the last third of the whorl is compressed and turned upward, 

 leaving a more or less marked furrow or channel on the correspond- 

 ing portion of the upper surface; the base is decidedly convex, 

 somewhat tumid, and is deeply, broadly constricted as it nears the 

 aperture, and has two diverging furrows behind the basal lip ; the 

 aperture is subhorizontal, ear-shaped, brown inside, obstructed by 

 three principal folds ; the peristome continuous, brown, expanded 

 and reflexed in every part ; its outer extremity has a recurved 

 sinuosity corresponding to the pinched-up carina of body- whorl ; the 

 basal lip is sinuous, and bears two teeth, the outer one is an elevated 

 plate, extending obliquely inward toward the axis, the inner tooth 

 is a stout entering fold ; the parietal callous is elevated and recurved ; 

 it gives rise to an arcuate lamina entering the aperture and almost 

 meeting the outer tooth of base ; there is a small acute lamina on the 

 superior wall of aperture opposite the outer basal tooth ; the umbilicus 

 is rather broad (5 to 6 mill.) and deep, partly occupied by the re- 

 curved inner angle or loop of the peristome. 



Alt. 20, diam. maj. 53, min. 44 mill. 



Alt. 18, diam. maj. 49, min. 41 mill. 



Alt. 15, diam. maj. 39, min. 31 mill. 



Isthmus of Panama ; Colombia; Panama, Ecuador. 



Helix labyrinthus (CHEMNITZ, Syst. Conchylien-Cabinet, xi, p. 271, 

 t. 208., f. 2048. 1795) DESHAYES in Guerin's Mag. de Zool., t. Ill, f. 

 1 (1837). PFEIFFER, in Kiister's Conchylien Cabinet, p. 61, t. 2, f. 

 5 ; Monographia Hel. Viv., i, p. 397. H. labyrinthus FERUSSAC, 

 Prodr., p. 33 ; Histoire, t. 54B, f. 5. REEVE, Conch. Icon., f. 550? 

 Carocolla labyrinthus (in part) An. s. Vert., vi, p. 96. Helix 

 otis of early English collectors ; Labyrinthus otis BECK, Index, p. 

 33. Lyrostoma labyrintha SWAINSON, Malacol. p. 329. Carocolla 

 subplanata PETIT, Rev. Zool., 1843, p. 238 ; Mag. de Zool., 1843, t. 



68. H. subplanata DOHRN, Jahrbiicher d. Mai. Gesell., 1875, p. 

 11 



