152 Transactions.— Zoology. 
borne on a fine suspensory membrane. Across the space between them 
stretch still smaller plume-like lamelle (id., fig. 2), each with a small 
capillary. These sub-lamelle 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. 8) on each 
side. 
| The renal organ (fig. 19) 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 (pl. vi.).—The male organs consist of a testis, vas deferens, 
** prostate" gland, duct of the “ prostate,” receptacle of spermatophores 
and penis. The testis (fig. 19) 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 1 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-rnarked transverse plico. Except that it narrows at either end, it is of 
about the same thickness throughout. It contains spermatozoa, which 
appear, when examined with the }-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 plice may possibly be due to only partial distention. 
The “ prostate” gland (fig. 1d; 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 cocal dilatation (4); and a 
similar dilatation is produced from the saccular portion from which the 
duct springs. 
