NEOBELISCUS. 281 



containing young, two of which occupy it at a time. The 

 uterus in virgin or functionally inactive individuals is 

 shrunken, and lies in numerous deep, regular, longitudinal 

 plaits. When carrying young at almost full term it presents 

 the appearance shown in fig. 5, the young lying with the head 

 directed anteriorly, the ventral face toward the sperm duct. 



V 



Albumen gland (figs. 4, 5, a. gl.) very small, shorter than 

 the talon and far smaller than the spermatheca. Median 

 moiety of the hermaphrodite duct extravagantly convoluted 

 and knotted. 



Viviparous; the shell of the young at birth (pi. 45, fig. 6) 

 is nearly one-fourth the length, and exceeds one-third the 

 diameter of the adult shells, with half the number of whorls. 



Retractor muscle system (pi. 45, fig. 7) somewhat resem- 

 bling that of Rumina; right, left and tail retractors free ex- 

 cept at the very insertion, where they are very shortly united. 

 Tail retractor or columellar muscle very long; right retractor 

 splitting up distally into (1) numerous anterior and lateral 

 pedal retractors, (2) the retractor of the eye, and (3) the re- 

 tractor of the penis. The left retractor gives rise (1) far 

 anteriorly to the short pharyngeal retractor which is shortly 

 bifurcate anteriorly, and (2) in front of this, splits into 

 ocular and pedal retractors. 



Lung (pi. 45, fig. 8) long and narrow, the venation faint, 

 mainly concentrated anteriorly and consisting chiefly of fine 

 parallel veins transverse to the pulmonary vein, which is 

 otherwise unbranched. Heart normal. Kidney more than 

 double the length of the pericardium, quite narrow, 'its length 

 contained about 3y 2 times in that of the lung. Ureter retro- 

 grade, continued along the gut, closed throughout. 



The jaw (pi. 45, fig. 3) is arcuate, densely striated, under 

 strong magnification showing transverse striolation in its sub- 

 stance, crenulating the vertical striae. 



Radula composed of 44, 1, 44 teeth in slightly bow-shaped 

 rows (pi. 45, fig. 1). Centrals very narrow, less than one- 

 fourth the width of the adjacent laterals, and bearing no 

 cusps in adult animals. Laterals with the basal plate wide 

 and square, tricuspid, the median cusp broadly conic, not as 



