A.R. MEAD 



BVD 



PIL 



RCR 



Fig. 1 Callistoplepa barriana, basal genital structures (MRAC no. 795.956). 



Fig. 2 C. barriana, right branch of columellar muscle showing posterior attachment of the penial retractor. 



Fig. 3 C. barriana, right ventrolateral view of penis to show the pilaster in profile. Contraction during preservation has telescoped the apical 



penis and forced it and its fibromuscular matrix out of the penis sheath. 

 Fig. 4 Callistoplepa shuttleworthi, penis sheath, permanently partially evaginated penis, and pilaster (containing the basal vas deferens) are 



shown in frontal plane and in dorsal view (UUZM). 

 Fig. 5 Same, in a slightly tangential sagittal plane. 



Fig. 6 Same, in ventral view with penis sheath cut longitudinally and spread laterally to show the penis within. 

 Fig. 7 Same, with penis cut longitudinally and spread laterally to expose the pilaster within. Penis sheath not shown. 

 Fig. 8 Same, with pilaster cut and spread to reveal the basal vas deferens opening dorsally into the lumen of the penis. The dense 



fibromuscular webbing at the junction of the basal vas deferens and penis has been removed for clarity. 



