36 ORGANS OF HESPTRATTOX, ETC. 



in contact with the water in tlie chamber becomes sack-like and 

 glanduhir. The pericardium and the sacks containing the testes 

 and ovaries, appear to communicate witli the i^allial cavity either 

 through these chambers or directl}-. 



The blood is a white liquid witli a slight tendency- to bluish, 

 and contains water S9 per centum, Albumen 3 per centum, Salts 

 and substances incoagulable by heat 7';') per centum, Kibvine, etc., 

 ■5 per centum. 



Valenciennes discovered in Nautilus three pairs of openings 

 connecting the branchial sack with five chambers ; of which the 

 anterior and posterior pairs situated on the sides of the rectum 

 are each provided with a single opening; whilst the fifth, a much 

 larger chamber, has an opening on either side. It is separated 

 by their walls from the otlier chambers ; and from the afteren 

 brancliial vcmus which traverse tlieso walls, lamellar appendages 

 project into the paired chambers, and papillated ones into the 

 single large chamber. In the smaller chambers are usually found 

 concretions of ]>hosphate of lime, without trace of uric acid. 



The gills form a cylinder in Octopus and Sepia, and in Loligo 

 and otiier genera they are in the form of a half-cylindei- : tliey 

 are two in number in the naked cephalopods, as well as those 

 possessing an internal shell ; anrl four, arranged a pair on each 

 side, in the Nautilus : hence the terms Dibranchiata and Tetra- 

 brancliiata, forming the highest divisions of the class Cephal- 

 opoda. The water finds access to the gills through the large 

 opening between the free anterior ventral margin of the mantle 

 and the bod}', and it is expelled from the fminel by a muscular 

 contraction of the wallof the mantle. 



The mantle is usually fastened dorsally l)y a muscular neck- 

 band or vuchal band, to the head of the animal, and this band 

 may ]»e either narrow^ or broad, or may even extend laterally 

 nearly around to the siphon : but usually the ventral margin of 

 the mantle, at least, is detached from the bod}': the degree of 

 attachment varies in the difiei'ent genera. "Within the mantle 

 opening are found the bi'anchi;e, the anus, the openings of the 

 generative and urinating organs, and of the ink-bag. 



L'rinary openings are found on each side of the rectum. The 

 urine is decidedly acid and limpid, and is filled with myriads of 

 infusoria and a great quantity of aggregations of little crystals 



