Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0201clau Year: 1884 82 MOLLUSCOIDEA. sisting of calcareous processes of the dorsal valve of the shell (fig. 555). They have the form of long appendages rolled up in a conical spiral on the anterior side of the body ; and they are traversed, as are the labial palps of many , by a groove. The edges of the groove give rise to close-set and long fringes composed of stiff II St' FIG. 556.—Development of Argiope (after Kowalevski). a, Larva, the gastric cavity of which has given rise to the drv
Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0201clau Year: 1884 82 MOLLUSCOIDEA. sisting of calcareous processes of the dorsal valve of the shell (fig. 555). They have the form of long appendages rolled up in a conical spiral on the anterior side of the body ; and they are traversed, as are the labial palps of many , by a groove. The edges of the groove give rise to close-set and long fringes composed of stiff II St' FIG. 556.—Development of Argiope (after Kowalevski). a, Larva, the gastric cavity of which has given rise to the drverticula of the body cavity (Lh); D, gut. b, Larva with three regions or segments, c, Larva with four bundles of seta? in the mantle-lobes of the middle segment, d. Later stnge. c, Attached larva with mantle lobes bent anteriorly, f, The tentacles (T) are developed ; St, peduncle. and movable filaments, the ciliated covering of which produces a strong current which leads small particles of food to the mouth opening. The heart is placed on the dorsal side of the anterior part of the intestine (stomach). It receives the blood through a venous trunk
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