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J. GRAHAM KERR. 



numerous caecal tubular outgrowths from the duct itself. 

 Beyond this point the duct opens into the spermatophore sac — 

 a large structure somewhat elliptical in outline when seen from 

 the anterior (dorsal) or posterior (ventral) aspect (PL X. fig. 1). 

 The vas deferens opens into this at its outer end. Internal to 

 this opening there begins a longitudinal septum which divides 

 the cavity of the sac through about half its length — terminating 



Diagram of the testis, genital duct, and penis of the male Nautilus. The rudi- 

 mentary genital duct of the left side is dotted in. 



T, testis : at its upper end is seen its aperture into the general cavity of the 

 ccelom. Ac.Gl, accessory gland with internal opening of the vas 

 deferens beneath the crescentic flap at its left-hand comer. Sp.Sac, sper- 

 matophore sac. 



The curved line traversing the diagram from side to side represents the line 

 along which the mantle-flap is reflected headwards. 



