Suhjamilies, Genera, and Subgenera — Recent and Fossil 177 



while in Planorbida this lamelhi points iiiiward. In Planorbula, the pHcae 

 are always present but in Tropicorbis they may be absorbed late in life and 

 the aperture become edentulous (see remarks under Tropicorbis) . 



Planorbula has also been subordinated to Segmentina as a subgenus 

 but it has no relationship to that genus, the internal organs being of a 

 totally different character. Segmentina is the type genus of the subfamily 

 Segmentininae. 



The chief characteristics of the genus Planorbula are the ovate or 

 rounded penial gland without an external duct but with a canal-like duct 

 within the preputium, and the prostate with small, branched diverticula 

 on one side of a main diverticulum. Its nearest relative is Proinenetus, with 

 which it agrees in general in the form of prostate and penial gland. These 

 genera and their relatives constitute a subfamily Planorbulinae, as sug- 

 gested by Pilsbry in 1934 (p. 47). 



Subgenus HALDEMANINA Ball, 1905 



Type by original designation Planorbis wheatleyi Lea 



1905. Holdemaniua Dall, Alaska Moll., p. 97. Type Pkmorbis wheatleyi Lea. As 



section of subgenus Planorbula Haldeman 

 1918. Haldemanina W.^lker, Miscel. Pub. Mus. Zool., Univ. Mich., Xo. 6, p. 105. Type 



Planorbis wheatleyi Lea. Synonym of Planorbula 

 1923. Haldemanina Germ.^in, Rec. Ind. Mus., XXI, p. 181. T3'pe Pla7iorbis wheatleyi 



Lea. Considered synonym of Planorbula 

 1931. Haldemanina Thiele, Handbuch, Teil 2, p. 480. T3-pe Planorbis icheatlcyi Lea. 



As synonym of Planorbula 



Shell (plate 79, figs. 28-30). As in Planorbula but with the aperture 

 notably thickened, the lower palatal lamella within the aperture very long 

 and curved upward as far as the upper palatal lamella. 



Animal. The animal is unknown anatomically. 



Geographical Distribution. Xot at present known outside of the state 

 of Alabama. 



Species Considered as Valid. Planorbula (Haldemanina) wheatleyi 

 (Lea). tyi)e of this subgenus, is the only species ascribed to it. 



Remarks. In 1905 (p. 97), Dall instituted a section Haldemanina to 

 contain the Planorbis wheatleyi of Lea. No particular characteristics 

 different from Planorbis armigera appear in his diagnosis, except the state- 

 ment 'lamellae complex.' Upon examining the lamellae of wheatleyi, the 

 complexity is at once seen. The lower palatal lamella is about twice as long 

 as in armigera and the upper part is bent upward almost at right angles 

 to the transverse lower part, so that this end is on a line with the upper 

 palatal lamella, the whole lamella being bent like an Australian boomer- 

 ang (see plate 76, fig. 9, wheatleyi; fig. 8, armigera). 



Authors, generally, have considered Haldemanina an absolute syn- 

 onym of Planorbula, but the difference in the lower palatal lamella is 

 persistent in all specimens of wheatleyi here examined and is not found in 

 any other species or race of Planorbula. The writer, therefore, is disposed to 

 accept Haldemanina as a subgroup under Planorbida. The thickening of 

 the lip has no special significance, as this is found in several species of 

 Planorbula. 



