336 I- IJIM^^ AXD S. IKEDÀ. 



Explanation of Plate XXXIII. 



Opisthoteuthis depressa Ij. & Ik. 



Fig. 1. 8ide-view. Nat. size. 



Fig. 2. Superior view. Nat. size. 



Fig. 3. Inferior view. Nat. size. 



Fig. 4. Ventral jaw. 3 x . 



Fig. 5. Dorsal jaw. 3 x . 



Fig. 6. Dorsal cartilage and its muscles exposed. 2 x . 



c, Cartilage. 



m, Muscle. 



/, Fin. 

 Fig. 7. Mantle-cavity exposed by incisions on either side of the branchial aperture 

 aud mantle thrown forwards so as to show its inner surface. About 2 x . 



a, Eeäected rim of the branchial' opening. 



IUI., Anus. 



h, Continuation of //, capable of being clasped by the button hut. 



}»■. lt., Branchial heart peering through the visceral wall. 



Init., Button. 



///., Gill. 



man., Inner surface of mantle. 



j)e., Penis. 



sejK, Septum of the mantle-cavity. 



*■/., Siphon. 



*■/. v.. Opening of siphon. 

 Fkj. 8. Eeproductive organs, diagraminatically represented. 



un.. Anus. 



jie., Penis. 



jir., Prostata. 



sp. Ä-., Spermatophore-sac. 



6-. v., Seminal vesicle. 



tes., Testis. 

 Fig. Ü. Hah-imaginary median section. 



