EXPEHIMEXT5 Df THE BBEEDIKG OF CEEIOXS. 11 



of the spermatic duct. The vagjna in aU the species examined is 

 attache<i to the left side of the atrium and is not clearly differentiated 

 from the oviduct above; it is vrithout folds. In Cerion inaimiTn, Cerion 

 Casablanca, Cerion vva, and Cerion crassQabris the spermatic duct 

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

 at the lower end. This is iL.st pronounced in Cerion inamum and 

 least so in Cerion casablanc/E. In Cerion viaregis it is attached about 

 halfway between the atrium and albmnen ^land. In Cerion incanum, 

 Cerion ca-iablanc'7. . and Cerion ura the spermatic duct is long and 

 slender and provided with a long flageUum near it s ujiper fourth. This 

 fiageUimi 'diverticulum of PiJsbry) is exceeiing'.y long in Cerion incanum 

 and is shortest in Cerion uva. It is variously dispceed am.ng the 

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

 incanum it loUc^v; the periphery of the whorls and its upper end is 

 near the apex. This oi^an is entirely absent in Cerion a-assHabris and 

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

 Pilsbiy and Vanatta. The spermatic duct in aU the species examined 

 foIlc~5 the vagina and o'dduct, to which it is ccseh' 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 flageUum, the last 

 remaining element of the sr-ermatheca. 



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

 nniscle by a heav}' 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 aU but Cerion crassU<Ari.i, in which it connects directly 

 vdth the cephahc retractor. The oviduct follows the columella of the 

 sbdl and is thin and membranous on the periphery, and sonievrhat 

 folded. The glandular tissue occupies a band along its inner mar^n. 

 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 

 tC' continue unmodified to the albumen gland. The albumen glsnd is 

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

 tine coiled about it in aU exc-ept Cerion cra-^silabris and Cerion viaregis, 

 in which it is free. The hermaphroditic duct ent«rs the concave margin 

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

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

 incanum, Cerion casablanoB, Cerion vva, and Cerion crassHabris this 

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

 crassilabris it is swoUen 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 tissi^e of the upper lobe of the liver, 

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



