THE CEPHALOPODA. 



449 



chamber can be fully distended without the air passing into 

 the other. 



Fig. 1^^.— Sepia officinalis. — <?. eystemichoart ; rto,antorinr aorta ; oo\ posterior aorta ; 

 1, vena cava; 2, afferent branchial ves.^els; re. mual ort;ai:8; z, appendages of 

 thef»e vessels; 3, 4, larsje posterior veins bringintr blood to the afferent branchial 

 vessel? ; 5, 6, 7, efferent branchial vessels, branchial veins, -and brauchio-cardiac 

 or auricular trunks. (After Hunter.) 



In ^aiitilics 2^ompilius there are, as Valenciennes discov- 

 ered, three pairs of openings which lead from the branchial 

 sac into chambers contained in the interior of the body. Of 

 these chambers there are five : the anterior and posterior 

 pairs are situated on each side of the rectum, and each has 

 its own opening ; the fifth, a very much larger chamber, has 

 two openings, one on each side. It is coextensive with that 

 part of the mantle which lies behind the insertion of the shell- 

 muscles and the hornv band which connects them. It is 

 separated from the paired chambers by their inner walls, and 

 these walls are traversed by the afferent branchial veins. 

 Appendages of these veins project on the one hand into the 

 paired chambers, and on the other into the single chamber. 

 The latter appendages are elongated papillae, while the for- 

 mer are lamellar. Earthy concretions, composed mainl}^ of 

 phosphate of lime, but which yield no trace of uric acid, are 

 usually found in the paired sacs.^ 



1 Owen, "Memoir on tlie Pearly Nautilus." Van der Hoeven, "Beitra^ 

 zur Anatomie vom I^aiitilus pompiluis^'' (" Archiv fiir Naturgeschichte," 

 1857). Huxlev, " On some Points in the Anatomy of Nautilus pompilius " 

 (" Proceedings of the Linnnpan Society," 1858). See also Keferstem, Bronn's 

 "Klassenu. Ordnungen," Bd. iii. (1862-'66), pp. 1390, 1319. 



