152 Transactions.— Zoology. 



borne on a fine suspensory membrane. Across the space between tliem 

 stretch still smaller plume-like lamella? (id., fig. 2), each with a small 

 capillary. These sub-lamella? look like repetitions of the entire gill ; but, 

 on microscopic examination, it is seen that they consist of a capillary 

 with a very thin membrane thrown into transverse folds (fig. 3) on each 

 side. 



The renal organ (fig. 1 g) is well-developed on the branches of the vena 

 cava. Two long lobes extend over the heart, which they almost hide ; and 

 each of these lobes has a well-marked opening, which communicates with its 

 branch of the vena cava. Thus, if air be blown into one of the openings, 

 it inflates its branch of the vena cava, and also the branchial heart into 

 which that branch opens. 



Reproductive Organs. 



Male (pi. vi.). — The male organs consist of a testis, vas deferens, 

 "prostate" gland, duct of the "prostate," receptacle of spermatophores 

 and penis. The testis (fig. lg) lies at the ab-oral end of the body, is 

 large, irregularly oval in outline, and flattened. Its lower outline is con- 

 cave, its upper convex. It is encased in a thin membrane attached on its 

 anterior surface and uniting it below with the inner anterior surface of the 

 mantle. 



The vas deferens communicates with the capsule of the testis towards 

 the upper end. Its commencement seems rather to be lost in the mem- 

 brane than to have a well-marked opening. It is short but slender, and 

 does not present the convolutions noticed in all descriptions of the male 

 organs of Cephalopods that I have seen. 



The vas deferens opens into a long, cylindrical vesicula seminalis, 

 which leads to the " prostate " gland. The walls of the vesicula present 

 well-marked transverse plica?. Except that it narrows at either end, it is of 

 about the same thickness throughout. It contains spermatozoa, which 

 appear, when examined with the J-in. objective, to be simple straight rods. 

 Though the walls of the vesicula appear to be thick and white, they are in 

 reality thin and transparent, the white colour being caused by the sper- 

 matozoa. The plicse may possibly be due to only partial distention. 



The "prostate" gland (fig. Id; fig. 2) is a delicate tube, presenting 

 marked convolutions, and having the appearance, when viewed on the 

 posterior aspect, of a spiral coil. At the point where the vesicula seminalis 

 enters it is dilated (3) ; then there is a strong convolution ; then a slightly 

 expanding tubular portion (2), which leads to a sac-like portion (1). Near 

 the point where the vesicula enters is a small ccecal dilatation (4) ; and a 

 similar dilatation is produced from the saccular portion from which the 

 duct springs. 



