Subfamilies, Genera, and Subgenera — Recent and Fossil 87 



uterus swells behind the vagina to more than twice the diameter of the 

 vagina. The nidamental gland is about as long as the uterus and is swollen 

 to twice the diameter of the uterus. The oviduct is shorter than the uterus 

 and rapidly narrows to meet the sperm duct. The albumen gland is a large, 

 elongate-ovate organ, half as high as long. 



Hermaphrodite Organs. Ovotestis apparently a double series of club- 

 shaped diverticula. The ovisperm duct is very narrow and its free por- 

 tion is about as long as the sperm duct. The seminal vesicle is placed nearer 

 the ovotestis than observed in the species of Tropicorbis examined. 



Pilsl)ry's figures of Planorbis adowensis Bourguignat (plate 71, figs. 

 10-12) are essentially the same in general generic characters as in pjeifferi 

 described above. The prostate (fig. 10) shows about sixteen short divertic- 

 ula which are unbranched. The penial complex (fig. 11) shows a wide, sac- 

 like preputium and a slender vergic sac equal in length to the preputium. 

 The retractor muscle is inserted at the junction of vergic sac and pre- 

 putium. Internally (fig. 12) the preputium has three vertical pilasters and 

 the verge is very long and slender. The spermatheca (fig. 10) is more 

 pyriform than that of pfcifferi and the duct is longer. 



The pseudobranch of Planorbis pfcifferi (fig. 7) appears to be folded as 

 it is in Tropicorbis. The figure of the digestive system (fig. 8) shows a wide 

 gizzard, a narrow and elongated pyloris, a narrow blind sac, and the intes- 

 tine looped about the stomach. The salivary glands form a short loop 

 behind the buccal sac. 



The above anatomical notes are drawn from the papers of Connolly 

 (1925) andPilsbry (1934). 



Geographical Distribution. Afroplanorbis appears to be distributed 

 over northern and central Africa and to include a number of species. 



Species Considered as Valid. The following are the species believed 

 to be referable to Afroplanorbis. Other species may be added when their 

 anatomy becomes known. 



Afroplanorbis sudanicus (von Martens) Afroplanorbis sudanicus tanganikanus 



Afroplanorbis pfcifferi (Krauss) (Bourg.) 



Afroplanorbis alexandriensis (Ebrenb.) Afroplanorbis bridouxianus (Bourg.) 



Afroplanorbis boissyi (Pot. and Mich.) Afroplanorbis adowensis (Bourg.) 



Afrdjihniorbi.'^ salinariDu (Morelet) Afroplanorbis paetcli (Jickeli) 



Geological Distribution. Not ascertained. The group is probably as old 

 as Tropicorbis. 



Remarks. The anatomy of Afroplanorbis sudanicus (von Martens) is 

 unknown, but the shell so closely resembles that of Afroplanorbis adowensis 

 (Bourg.) that they appear to be congeneric. Pilsbry (1934, p. 54) calls at- 

 tention to the similarity of the shells. He also dissected Planorbis adowensis 

 (his figures are copied on my plate 71) and found the anatomy to be very 

 much like that of Tropicorbis. Connolly (1925, plate 8) figures the genitalia 

 of Planorbis pfcifferi Krauss and his figure differs little from that of 

 Pilsbry except in specific details. The branched diverticula of the prostate 

 are believed to be attributed to faulty drawing rather than to real differ- 

 ences in structure. The chief difference between Tropicorbis and Afropla- 

 norbis appears to be in the longer seminal vesicle of the latter, the smaller 

 number of prostate diverticula, the greater size of the uterus and nida- 

 mental gland, and the greater difference in diameter between the preputium 

 and vergic sac. 



