690 PROCEEDINGS OF THE ACADEMY OF [DeC, 



on the right side of the head, leads into a small atrium with which 

 the penis, hermaphroditic duct, and seminal receptacle attach. 

 The first named is a heavy, muscular organ, accompanied by the 

 usual slender vas deferens, their union being effected at some distance 

 from the distal end of the penis, which thus forms a flagellum (PI. 

 XXXI, fig. 7, f). As the flagellum thus holds identically the same 

 position as the so-called penis retractor in A. ringeris, I am strongl}^ 

 inclined to the opinion that we are actually dealing with flagella in 

 both instances. In the present specimen the penis and flagellum 

 are both sharply defined and appear to be without muscular attach- 

 ments, though bound to the body wall by delicate connective tissue 

 strands. In the neighborhood of the outer opening, however, the 

 penis sheath affords attachment for three or four slender muscle 

 bands that I am inclined to regard as penis retractors. 



The hermaphroditic duct, a highly glandular duct of comparatively 

 even diameter, traverses the greater portion of the first coil of the 

 body to enter the accessory glands. All of these structures are in a 

 quiescent condition, and in size and configuration probably fall far 

 short of their fully developed state in the sexually mature condition. 

 The same is likewise true of the gonad. While the duct leading to 

 it from the accessory glands is clearly apparent throughout the first 

 part of its course, it gradually approaches the vanishing point, and 

 cannot with certainty be traced to a gonad, which is accordingly 

 drawn in its hypothetical position. 



Two living specimens of Tomigerus clausus were found beneath 

 stones in the vicinity of Ceara-Mirim, a town about midway between 

 Baixa Verde and Natal. Both were in a state of aestivation, and 

 failed to revive, though kept in a moist chamber for several days. 

 It is evident from several features of the shell and internal organiza- 

 tion that the shell in this genus is carried with its principal axis 

 transverse to the longitudinal axis of the foot; that is, the spire is 

 directed to the right. The flattened surface of the outer whorl thus 

 rests upon the dorsal surface of the foot or upon the substratum 

 when the animal is in a state of aestivation, a position which they had 

 assumed in both instances. 



As each individual was in a highly contracted state, with foot and 

 head drawn far within the shell, external features are difficult to 

 determine. It appears certain, however, that the mantle, with 

 more highly thickened margins and more glandular epithelium than 

 in Anosto7na, extends throughout the first whorl of the shell to the 

 region adjacent to the aperture. It thus terminates at the point 



