366 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [156] 



Notes on the visceral anatomy of Loligo Pealei. 



(See Plate XX, fig. -2; Plate XXIX. figs. l-3a; Plate XXXII, figs. 2, 3.) 



The gills (g) are large and highly organized in this species, although 

 considerably smaller than in Omm a st replies. The bases of the gills (g) 

 are situated somewhat in advance of the middle of the mantle-cavity, or 

 branchial chamber, and their tips, in fresh specimens, extend forward 

 nearly to the base of the siphon (/). The branchial chamber is separated 

 from the visceral cavity by a thin translucent membrane (the so-called 

 peritoneal membrane), through which there are two circular openings 

 (w), one a short distance in advance of the base of each gill; through 

 these the secretion of the urinary organs (r,r') is doubtless discharged. 

 Internally the visceral cavity is divided into several compartments by 

 folds of thin membrane. The largest of these chambers contains the 

 stomach and its cceeal lobe (S, S'). When the branchial cavity is 

 opened on the ventral side, as in PI. XXIX, fig. 1, and the thin mem- 

 branes covering the viscera are removed, the renal organs (r, r 1 ) are 

 seen as large and conspicuous organs, especially if the venous system 

 has been injected with a colored fluid. These organs are mostly situ- 

 ated close around the heart, above, below, and in front of it, but two 

 of them, in the form of pyriform glands (r', r'), which are firmer and 

 have a more compact structure than the rest, extend along the pos- 

 terior vense-cavse. These extend forward and unite with the two 

 elongated, saccular organs (r, r), which extend across the ventral side of 

 the heart and the bases of the gills, and passing farther forward, unite 

 on the dorsal side of the intestine to form the anterior vena-cava; 

 before they thus unite each one receives a vein from the intestine (r") 

 and gives off a large sacculated vessel, or branch, which, passing 

 upward along the sides of the proximal part of the intestine, unite with 

 two large lobulated renal sacs, which lie above and in front of the heart 

 and surround the commencement of the intestine; these send tapering 

 lobes backward, which receive the blood from the gastric veins; anteri- 

 orly they receive the hepatic veins; laterally they receive the large ves- 

 sels or pallial veins from the sides of the mantle, and also communicate 

 with the branchial auricles. 



The heart (H) is a large, muscular, and somewhat unsymmetrical 

 organ, varying in shape according to the state of contraction. Usually 

 it is more or less obliquely four-cornered, with the right side largest and 

 the posterior end more or less conical. From the posterior end arises a 

 large artery, the posterior aorta, which gives off, close to its origin, two 

 small arteries; one of these is median arid goes forward to the ink-sac 

 and intestine, passing below and across the heart; the other, arising 

 laterally, in the male goes to the prostate gland and other organs 

 connected with it (PI. XXIX, fig. 2, po). A little farther back the pos- 

 terior aorta divides into three large arteries; one of these (o) is situated 

 in the median plane, and, crossing the branchial cavity along the curved 





