Figure 165. — Apha/tosloma album. 



77 (73) Rhabdites absent; male antrum lacking; seminal vesicle present or absent 78 



78 (77) Seminal vesicle absent; penis a simple invagination of outer wall layers with a ball of sperm at the proximal 



end that is surrounded by a parenchymal net with a few muscle fibers and gland cells (Fig. 166) 



Genus Proconvolula. 



Figure 166. — Procnnvoluta primitiva. 



78 (77) Seminal vesicle present; penis a tubelike invagination which is further invaginated into the seminal vesicle 

 (Fig. 167) Genus Proaphanostoina. 



Figure 167. — Proaphanostoma lenuissima. 



51 



