374 PROCEEDINGS OF THE ACADEMY OF [1899, 



Fig. 8. Callioiiejnon Iherhigl. Genitalia X 3;^. Letters as for 



fig. 5; X,, hollow sack. No. 73,454, coll. Acad. 



Nat. Sci. Phila. 

 Fig. 8a. Diagram showing the relation of the cephalic branch of 



the aorta {ao. ) to the gut (G'', G^) and spermatheca 



(sp.). H., heart. 



Plate XVI. 



Fig. 9. Neobelisciis calcareus. Free retractor muscles, dorsal 

 aspect. br., branch of left retractor; I. o. r., left 

 ocular retractor; I. r., left retractor; 2>-, penis; ^;/t., 

 pharynx, or buccal mass; ph. r., pharyngeal retractor; 

 p. r., retractor of the penis; r. o. r. , right ocular 

 retractor; r. r., right retractor; r. /. v., right tenta- 

 cular retractor; t. r., tail retractor. 



Fig. 10. Rumina decoUata (L. ). Free retractor muscles X 2, 

 dorsal aspect. Lettering as in preceding figure. 

 Specimen from Malta, No. 72,504, coll. Acad. Nat. 

 Sci. Phila. The pharynx and pharyngeal retractor are 

 removed from their normal median position, and placed 

 to the left. 



Fig. 11. Calllonepion Iheringi. Shell, natural size. No. 71,258, 

 coll. Acad. Nat. Sci. Phila. 



Fig. 12. Apical whorls of same, much enlarged. 



Fig. 13. Aperture of same, enlarged. 



Fig. 14. Neobeliscus calcareus. Intestine and pallial region, 

 slightly less than natural size. G^'*, four folds of the 

 gut; g. u. v., secondary ureter; H., heart; k., kid- 

 ney ; p. v., pulmonary vein ; st. , stomach ; ur. , ureter. 



Fig. 15. Rumina decollaia. Intestine and pallial region X 2. 

 p>h., pharynx; s. g., salivary gland. 



Fig. 16. Pharynx and salivary gland, ventral aspect, X 2, of the 

 same specimen. 



Fig. 17. Genitalia, X 2, of the same specimen. 



