. Elements of comparative anatomy. Anatomy, Comparative. VASCULAK SYSTEM OF MOLLUSCA. 373 o©\© from the ccclom is collected into canals, which run in the integu- ment; and thence it is distributed to the gills. All the blood, how- ever, does not pass to them, for some is returned to the heart after having passed through the integument. In Helix and Limax the haemal spaces, which pass into the wall of their branchial cavity, and which form a system of canals which carries blood to the res- piratory organs, are de- veloped in a vascular manner. They break up into a rich network in the integument
. Elements of comparative anatomy. Anatomy, Comparative. VASCULAK SYSTEM OF MOLLUSCA. 373 o©\© from the ccclom is collected into canals, which run in the integu- ment; and thence it is distributed to the gills. All the blood, how- ever, does not pass to them, for some is returned to the heart after having passed through the integument. In Helix and Limax the haemal spaces, which pass into the wall of their branchial cavity, and which form a system of canals which carries blood to the res- piratory organs, are de- veloped in a vascular manner. They break up into a rich network in the integument, and this network gives off a number of large trunks with distinct walls, which unite to form a " pulmonary vein ; " and this vein passes into the auricle. The network of pulmonary vessels may be regarded as a large blood sinus, which extends into the walls of the lungs, and which is broken through at various points by islets of firm substance. § 287. The heart of the Cephalopoda is placed at the base of the vis- ceral sac, and is formed of a rounded or trans- versely - oval ventricle (Fig. 195,BG; Fig. 199, c), which receives blood from as many bran- chial veins as there are. Fig. 199. Anatomy of Octopus. Mantle-cavity and visceral sac, opened from the ventral surface, ph Pha- rynx, gls s Superior salivary glands, gls i Inferior salivary glands, o Eye. i Funnel, br Branchiae. ov Ovary, od Oviduct, c Heart, v Ir Branchial veins. a Arteria cephalica. vc Arenas cavas. av Venous appendages (after Milne-Edwards.) branchiae. That is to say, in Nautilus there are four, and in the rest of the Cephalopoda two branchial veins opening into the ventricle. These veins are generally considerably widened out in front of their opening into the ventricle (Fig. 199, v br), and this enlargement is homologous with the auricle in the Gastropoda and Lamellibranchiata. Two arterial trunks always arise from the heart; one, the larger, passes straight forwards; this is the arteria cephal
Size: 1269px × 1968px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1870, booksubjectanatomycomparative
