. A textbook of invertebrate morphology [microform]. Invertebrates; Morphology (Animals); Invertébrés; Morphologie (Animaux). TYPE ANNELIDA. 249 The only sense-orgaus which have beeu described are a pair of ciliated depressious lyiug one on each side in the concavity of the lophophore ; no definite statement can be made as to their function. A single pair of nephridia is present, opening into the posterior chamber of the coelom by fuuuel-like mouths, and to the exterior on each side of the anus. They serve not only for excretion, but also as ducts for the reproductive elements. The various spe
. A textbook of invertebrate morphology [microform]. Invertebrates; Morphology (Animals); Invertébrés; Morphologie (Animaux). TYPE ANNELIDA. 249 The only sense-orgaus which have beeu described are a pair of ciliated depressious lyiug one on each side in the concavity of the lophophore ; no definite statement can be made as to their function. A single pair of nephridia is present, opening into the posterior chamber of the coelom by fuuuel-like mouths, and to the exterior on each side of the anus. They serve not only for excretion, but also as ducts for the reproductive elements. The various species of Phoronis, \yith the possible exception of P. arcMteda, are hermaphrodite, the ova and spermatozoa developing from cells of the peritoneum lyiug in the vicinity of the pouched longitudinal blood-vessel. They are shed from their place of formation into the coelomic cavity and thence pass to the exterior through the Frd. 118.—Metamoki'Iiosih of Actinotrochn (after MitTsrHNiKOFF from BALrot'R). in = invMiiiiiMfion. Development of the Phownida-.—Iu their deve'opmeut the various species of Phoronis ho far as kuowu undergo a very r.'inarlaible metamorphosis. Tlie larva which develops from the ovum is knowji as Actinotrochn (Fig. 113, ^)aud is a some, what eloijgated Htructure possessiug at the anterior end a large hood which overhangs the mouth, its edge bearing. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original McMurrich, J. Playfair (James Playfair), 1859-1939. New York : H. Holt
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