AGNATHOMORPHA. IX 



The position of Selenochlamys is uncertain. The genus 

 is known only from two immature specimens. The keeled 

 tail is like Trigonochlamydince, but the greatly reduced lunate 

 mantle close to the end of the tail, and the apparent absence 

 of a shell-plate, are peculiar features. 



SUPERFAMILY AGNATHOMORPHA. 



AGNATHOMORPHA are rapacious snails having no distinctly 

 developed pedal grooves, the foot-borders being similar to 

 those of Helicidce etc. Lateral grooves, diverging forward 

 from the mantle such as occur in Testacella, are not present, 

 though there may be a groove from mantle-margin to the 

 genital pore, such as that occasionally distinguishable in 

 Holopod snails. The teeth are all thorn-shaped, with single 

 simple aculeate cusps. The shell is ordinarily well developed, 

 but there are exceptions (Apera, Schizoglossa, Strebelia) 

 where it is reduced and incapable of containing the whole 

 animal. The cerebral ganglia are concentrated, in close con- 

 tact. A jaw is developed in the Circinariida, absent or 

 merely vestigeal in the other groups. 



The affinities of this superfamily are with the Holopoda of 

 my classification. The five families are apparently natural 

 groups, but the want of anatomical data upon many genera 

 leaves their characterization imperfect. 



a. Mantle apparently wanting, or restricted to a shell sack; 



there is a vestigial shell-plate under a posterior foramen. 



No jaw. Body slug-like, widest posteriorly. South 



Africa. Aperida. 



a 1 . Mantle well developed, bearing a spiral external shell. 



ft. Pulmonary vein having numerous lateral branches, 

 the venation of the lung sufficiently coarse to be dis- 

 tinct. No coherent jaw. 



c. Shell Heliciform or Piano rboid, (rarely re- 

 duced, Sigaretus-like), usually with distinct 

 colored cuticle. Kidney lying parallel to the 

 pericardium, which it surpasses in length. 

 South Africa, Australasia. Rhytidid&. 



