58 ANATOMY OF ACHATINELLID^E. 



distinguishable from the marginal teeth. We believe that 

 the narrow central, when present, is merely a modified mar- 

 ginal tooth, and not homologous with the central tooth of 

 normal radulas. These characters are shown in pi. 20, fig. 2, 

 A. lorata nobilis, a tooth in profile at x, and pi. 20, fig. 1, A. 

 vulpina. 



The forms of the teeth are almost exactly similar in many 

 species of Achatinclla, Achatinellastrum, Bulimella, Partu- 

 lina, Eburnella, Perdicella, Baldwinia and Newcombia, ex- 

 amined by Mr. W. G. Binney, H. M. Gwatkin, H. Suter and 

 the writer. 



The salivary glands are united above, and less broadly 

 below the oesophagus, which is long and not dilated to form 

 a crop. The stomach is long, cylindric, produced at the py- 

 loric end. The intestine is long. As usual, the alimentary 

 canal lies in four folds. 



Reproductive organs (plates 12, 13, 14). The terminal 

 male organs are drawn isolated in pi. 13, fig. 4. The penis 

 (p.) branches into a long appendix (app.) which is enlarged 

 a little towards the distal end, more at the proximal end, and 

 is very slender in the middle. The penial retractor muscle 

 (p. r.) is bifid, one branch being inserted at the apex of the 

 penis, the other on the enlarged basal part of the appendix. 

 The vas deferens is terminal on the penis, and lies free from 

 the uterus. There is no flagellum. The vagina is extremely 

 short. Spermatheca globular, lodged among the caeca of the 

 prostate gland, in which it is more or less completely im- 

 bedded (see pi. 13, fig. 3, right side). Its duct is very long, 

 and not branched. The uterus is narrow below, but usually 

 much enlarged above. It usually contains but one embryo 

 in an advanced stage at a time (see pi. 13, fig. 3, the embryo 

 showing through the transparent wall of the uterus). 



The ovotestis is imbedded in the uppermost part of the 

 digestive gland. The albumen gland is very minute (pi. 12, 

 fig. 1, a. gl.), and in some species could not be found. The 

 prostate gland is enormously developed, consisting of a large 

 mass of long tubules (drawn on the left in figures 2, 5, 6, of 

 plate 12). 



