ACANTHINULA. 281 



'fig. 11, A. lamellata, after Lehmann) apparently lacking mucus 

 glands, but dart sack present. 



Distribution, Palrearctic and Nearctic regions, mainly northward. 



The genitalia are very imperfectly known, the figure in Lehmann's 

 posthumous work representing A. aculeata being very much like a 

 Buliminus or Pupa, and possibly, as v. Ihering suspects, inserted 

 through some confusion of drawings. A new investigation is 

 urgently required. Possibly the group does not belong to the Heli- 

 cidse. A. lamellata and aculeata have been found in Pliocene 

 deposits; and in the lower Miocene of middle Europe the genus is 

 represented by several species, A. nana A. Braun, paludiniformis 

 Br., tuchoricensis Klika, plicatella Reuss. 



A. aculeata Miill.,iii, 53. A. lamellata Jeffr., iii, 54. 

 spinulosa Lightf. scarburgensis Alder. 



granatelli Biv. seminulum Rossm. 



delectabilis Sol. A. peracanthoda Bgt., iii, 54. 

 /. albida Jeffr., iii, 53. raffrayi Bgt. not Canef. 



albino, West. raffrayana Ckll. 



v. sublsevis West., iii, 54. A. spinifera Mouss., iii, 54. 



A. spermatia Silva. A. monas Morel., iii, 54. 

 A. harpula Reinh. 



Section Zoogenites Morse, 1864. 

 Zoogenites MORSE, Terr. Pulm. Maine, p. 32, pi. 1. 



Shell globose-turbinate, perforate, ornamented with oblique cuti- 

 cular lamellae. Type Z. harpa Say, pi. 70, figs. 23, 24, 25. 



Animal with the foot-edges prominently crenulated ; labial lobes 

 large ; lower tentacles nearly obsolete ; viviparous, the young at 

 birth as large as the aperture of the shell. Jaw (pi. 70, fig. 35) 

 having numerous wide subobsolete ribs. Radula with formula 

 11.6.1.6.11. Middle teeth tricuspid, the mesocone not reaching edge 

 of the square basal plate. Laterals bicuspid. Marginals wide, 

 with many irregular cusps. Genitalia unknown. 



A. harpa Say, iii, 54. New England, British America, Sweden, 

 Kamtchatka, etc. 



Syn. : P. costulata Mich., H. amurensis Gerstt. 



