INTRODUCTION. XI 



Tandon's figure of the penis of Pagodulina to that of Orcula. 

 The homologies of the penial appendages of Orcula and 

 Orculella have been discussed by H. Burrington Baker, p. 201, 

 whose conclusions appear well founded. 



Orculella, distinguished from Orcula by the possession of 

 an appendix, and a shorter spermathecal duct, does not appear 

 to have any conspicuous differential shell characters. It is 

 this group which approaches the Pupillinae closely, but has 

 not the bifid penis or forked retractor. 



Subfamily Nesopupinae. 



Nesopupinae Steenberg, 1925, p. 201. For anatomy see 

 H. B. Baker, p. 204. 



Vertigininae, part, Pilsbry, 1920. 



Shell and animal substantially like Vertigininae except that 

 the penis bears an appendix and the retractor muscle is 

 forked. Part of the genera are viviparous. 



The genera composing the Nesopupinae had been grouped 

 in a continuous series in my monograph of Vertigininae. 

 Further anatomical work is needed to confirm the constancy 

 of the differential characters of the two subfamilies, which 

 are clearly more closely allied than either is to any other. 



It is an old group of world-wide distribution in tropical 

 and subtropical zones ; it comprises a number of extinct genera, 

 and is now largely replaced in northern continents by the 

 Vertigininae, which were apparently derived from nesopupoid 

 ancestors by simplification of the male organs. Starred 

 genera have been dissected. 



Campolaemus, 25:364. Staurodon, 25:224. Ptychalaea, 

 25:273; 27:225. *Lyropupa, 25:226. *Nesopupa, 25:274. 

 Costigo, 25 :336. *Pronesopupa, 26 :1. *Bothriopupa, 24 :226 ; 

 27 :228. *Pupisoma, 26 :19. Cylindrovertilla, 26 :43. Sterkia, 

 26:49. Paracraticula, 27 :221. Glandicula, 25 :221. Pseudelix, 

 25 :222. 



The fifth to eighth genera of the above list are evidently 

 closely allied, and whether all are generically distinct seems 

 open to question. Ptychalaea may belong to the Vertigininae. 



