Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0201clau Year: 1884 14 MOLLUSCA. poda\ They usually have the form of sacs with a wide lumen, and open on the one hand into the body cavity (pericardial sinus), and on the other to the exterior by a lateral opening. In all probability the mol- luscan kidney is homologous with an annelidan segniental organ. The internal, funnel- shaped opening is frequently beset with cilia. The anus is very often removed from the middle line, and placed on one side of the body. A compact heart is always present, driving the
Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0201clau Year: 1884 14 MOLLUSCA. poda\ They usually have the form of sacs with a wide lumen, and open on the one hand into the body cavity (pericardial sinus), and on the other to the exterior by a lateral opening. In all probability the mol- luscan kidney is homologous with an annelidan segniental organ. The internal, funnel- shaped opening is frequently beset with cilia. The anus is very often removed from the middle line, and placed on one side of the body. A compact heart is always present, driving the blood through the vessels into the organs. The vascular system is never completely closed, for, even when the arteries and veins are connected by capillaries, blood sinuses, de- rived from the body cavity, are inserted into the course of the vessels. The heart is always arterial—, systemic and receives arterial blood from the respiratory organs. Respiration is in all cases carried on through the general outer surface of the body ; but in addition special respiratory organs, in the form of Iranchiw, more rarely of lungs, are present. The branchiae are ciliated projections of the body sur- FIG. 497. - Nervous system of Cuuidaria (after d usually placed Haller). Cg, cerebral ganglion; Pg, pedal r ganglion; pig, pieurai ganglion; Bg, buccai between the mantle and the ganglion; G»p, supraintestinal ganglion; Gib, ^ave the subintestinal ganglion; , visceral ganglion; o/.otocyst. form of branched append- ages or of broad lamella (LamcUibrancMata}. The lung, on the other hand, is derived from the mantle cavity, which is tilled wi V
Size: 911px × 2194px
Photo credit: © Bookworm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: archive, book, drawing, historical, history, illustration, image, page, picture, print, reference, vintage
