MOLLUSCA CEPHALOPODA. 



09 



gullet is provided with salivary glands. The intestine 

 opens on the ventral surface near the base of the funnel. 

 This funnel is a muscular tube, situated under the 

 head. It communicates at one extremity with the cavity 

 of the mantle, and at the other with the external medium. 

 The naked cephalopods are provided with a gland called 

 the ink bag, which opens into the gill chamber near the 

 anus. It discharges its contents through the funnel, 

 and darkens the water, thus covering their retreat when 

 pursued by an enemy. 



131. Circulation. The blood is colourless. The heart 

 contains two cavities, an auricle and a ventricle. The 



Fio. 41. A, OCTOPUS OR POULPE; J5, THE MANTLE OF THE POULPE REMOVED 



FROM THE RIGHT SIDE. 



&, the right gill ; o, the free margin of the branchial sac ; t, the funnel. 



aerated blood from the gills passes into the auricle, thence 

 to the ventricle which drives it through the body. In 

 the cuttle-fishes, at the base of each gill, there is a special 

 cavity which by its contraction drives the venous blood 



