EXPERIMENTS IN THE BREEDING OF CERIONS. 11 



of the spermatic duct. The vagina, in all the species examined is 

 attached to the left side of the atrium and is not clearly differentiated 

 from the oviduct above ; it is without folds. In Cerion incanum, Cerion 

 casablancce, Cerion uva, and Cerion crassilabris the spermatic duct 

 enters the vagina slightly behind the atrium. In all of these it is largest 

 at the lower end. This is most pronounced in Cerion incanum and 

 least so in Cerion casablancce. In Cerion viaregis it is attached about 

 halfway between the atrium and albumen gland. In Cerion incanum, 

 Cerion casablancce, and Cerion uva the spermatic duct is long and 

 slender and provided with a long flagellum near its upper fourth. This 

 flagellum (diverticulum of Pilsbry) is exceedingly long in Cerion incanum 

 and is shortest in Cerion uva. It is variously disposed among the 

 viscera, but is not folded in any of the species examined. In Cerion 

 incanum it follows the periphery of the whorls and its upper end is 

 near the apex. This organ is entirely absent in Cerion crassilabris and 

 Cerion viaregis. It has also been recorded absent in Cerion yumaense 

 Pilsbry and Vanatta. The spermatic duct in all the species examined 

 follows the vagina and oviduct, to which it is closely adherent. The 

 spermatheca may be globular or slightly elongated. In Cerion viaregis 

 it is entirely absent. In this case it may be possible that what we have 

 called the spermatic duct may in reality be the flagellum, the last 

 remaining element of the spermatheca. 



The vagina is attached at the lower end to the right cephalic retractor 

 muscle by a heavy band of muscle, which is in two parts in Cerion 

 incanum. The right ocular retractor is attached to the vagina at the 

 same point in all but Cerion crassilabris, in which it connects directly 

 with the cephalic retractor. The oviduct follows the columella of the 

 shell and is thin and membranous on the periphery, and somewhat 

 folded. The glandular tissue occupies a band along its inner margin. 

 It contains gelatinous matter which swells and bursts the walls when 

 the organ is placed in contact with water. These observations do not 

 obtain in Cerion viaregis. In this form there is no apparent differentia- 

 tion in structure between the vagina and oviduct. The former appears 

 to continue unmodified to the albumen gland. The albumen gland is 

 situated at the upper end of the oviduct and has the loop of the intes- 

 tine coiled about it in all except Cerion crassilabris and Cerion viaregis, 

 in which it is free. The hermaphroditic duct enters the concave margin 

 of the albumen gland as a slightly convoluted tube and follows the 

 columella of the shell upward to the hermaphroditic gland. In Cerion 

 incanum, Cerion casablancce, Cerion uva, and Cerion crassilabris this 

 duct is colored dark brown or black in its lowest portion. In Cerion 

 crassilabris it is swollen in the lower part. In Cerion viaregis it is a 

 simple straight duct without convolutions or pigment. The hermaph- 

 roditic gland is embedded in the tissue of the upper lobe of the liver, 

 to which it is firmly attached. The color of the two is the same and 



