HELICODONTA. 289 



H. parryi Pons. & Sykes. H. everia Mab., iii, 123. 



H. afficta Fef., iii, 122. H. marcida Sh., iii, 123. 



H. planaria Mouss., iii, 122. H. crispolanata Woll, iii, 123. 



H. discobolus Sh., iii, 123. H. beata Woll., iii, 123. 



H. fortunata Sh., iii, 123, H. gomerse Woll., 123. 



H. pthonera Mab., iii, 123. H. eutropis Shutt. iv., 36. 



Section Klikia Pilsbry, 1894. 



Shell depressed-globose, narrowly umbilicated, with convex, ob- 

 tuse spire and round periphery. Surface costulate-striate and 

 minutely papillose in regular diamond pattern. Last whorl con- 

 stricted behind the lip, which is well reflexed and thickened. Type 

 H. osculum Thomae, pi. 71, fig. 49. 



This apparently extinct type of Helicodonta is characteristic of 

 middle European Miocene, where it coexisted -with species of Cara- 

 collina, such as phacodes Thomae, and with species of typical Heli- 

 codonta ; H. involuta Thomae being allied to the recent angigyra 

 and biconcava. The strong differentiation of these sectional groups 

 at as early a period as the lower Miocene (when they were, in fact, 

 as strongly differentiated as in the recent fauna), argues a vastly 

 greater antiquity for the genus as a whole. This group is named in 

 honor of Gottlieb Klika, author of an excellent memoir upon tertiary 

 land and fresh-water shells of Bohemia. 



Subgenus MOELLENDORFFIA Ancey, 1887. 



Mollendorfia ANC., Conch. Exch., May, 1887, p. 64. PILSBRY, 

 Man. Conch., vi, p. 10. Proctostoma MABILLE, Bull. Soc. Mai. de 

 France, iv, p. 102, 103,104,1887 (for H. loxotatum^.Polygyra and 

 Cepolis of some authors. Trihelix ANC., t. c., p. 64 (for H. horrida). 



Shell depressed, with low-convex, flat or concave spire of 4%-5? 

 whorls, rounded or keeled periphery, and convex, umbilicated base. 

 Surface more or less granular, tubercular or hairy, uniform brown, 

 dull and opaque. Apical whorl rather large ; last whorl deeply de- 

 flexed in front, with deep pits or grooves behind the lip. Aperture 

 very oblique or subhorizontal, trigonal or squarish, the lip expanded 

 and reflexed, continuous across the parietal margin, sometimes solute ; 

 basal lip armed with a stout tooth, outer lip with one or two large en- 

 tering folds. Type H. trisinuata Martens (see pi. 40, figs. 16, 17, 18, 

 H. hensaniensis Gredl.; pi. 56, figs. 20, 21, 22, H. erdmanniSchmaclu.? 

 & Boettger). 

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