AND THE MALES OF CERTAIN CEPHALOPODS. 153 



exhibit the organs in their natural position. The letters a h have 

 the same signification as before, i, abnormal arm, i. e. the Hectoco- 

 tylus ; k, the anus ; /, the rectum ; m, the large intestine ; n, the ink- 

 bag ; o, the ventral aorta ; p, the venous appendages. 



Fig. 3. The genitalia with the branchiae, the hearts, and the large intestines, 

 wholly detached and seen from the ventral side. The letters as in 

 the foregoing figures, q, cornu ; r, testicle ; ^, aortic heart. 



Fig. 4. The abdominal organs seen from the dorsal side, t, stomach ; u, caecum; 

 v, liver ; w, dorsal aorta. 



* # * These four figures are twice the natural size. 



Fig. 5. Abdominal organs of the female T. Carena, seen from the ventral side. 

 Natural size. The mantle is thrown back; the fibrous envelope of 

 the abdomen is taken away : for the rest the organs are in their na- 

 tural position, a, funnel; b, anus; c, branchiae; d, branchial hearts; 

 e, venous appendages ; /, sexual apertures ; g, ovary. 



Fig. 6. The sexual organs isolated, seen upon the ventral surface and mag- 

 nified twice, a a, oviducts ; &, ovary ; c c, ova passing along the 

 oviduct. 



PLATE III. 



Figs. 1 4. The male sexual organs magnified 2 diam. completely detached 

 and viewed (figs. 1 & 3) from the ventral side, and (figs. 2 & 4) 

 from the dorsal side, a, flask with the aperture and the sperma- 

 tophore ; b, cornu ; c, testicle with the efferent canal. 



Fig. 5. The cornu is open for its entire length. The deferent canal and the 

 accessory gland are unrolled, a, continuation of the cornu into the 

 neck of the flask ; 6, common reservoir ; c, aperture of the deferent 

 canal ; d, aperture of the excretory canal of the gland ; d', deferent 

 canal ; e e, clavate enlargements ; /, seminal mass contained in the 

 canal ; g, pyriform enlargement ; h, globular gland ; i, aperture of 

 the deferent canal ; k, envelope of the cornu ; I, excretory canal of 

 the accessory gland ; m, accessory gland ; n, efferent canal ; o, enve- 

 lope of the testicle ; p, testicle. 



Fig. 6. Contents of the seminiferous tubes. X 400. 



Fig. 7. Structure of the efferent canal. 



Fig 8. Glandular sac of the accessory gland. X 400. a, capillaries. 



Fig. 9. Seminal mass contained in the deferent canal. Posteriorly, only the 

 contour of the felted spermatozoa and the traces of the developing 

 transparent thread are indicated. , transparent thread. 



PLATE IV. 



Fig. 1 . Spermatophore withdrawn from the flask. 



Fig. 2. Th6 anterior extremity of the same, considerably magnified and viewed 



by transmitted light, a, transparent envelope ; b, ejaculatory cord ; 



c, seminal cord. 

 Fig. 3. Posterior extremity of the ejaculatory cord in connexion with ihe 



seminal cord, a, seminal cord ; b, fine membrane applying itself to 



