Text-book of comparative anatomy . each side. These become the permanentnephridia of the adult Phoronis. The Actinotoocha thus formed sinks to the lioiiomof the sea ; the invaginated trunk protrudes and grows quickly, the mid-gut at thesame time entering it and forming a loop with ascending and descending whole prostomium, with the neural plate and the larval tentacles, are thrownoff and devoured by the young Phoi-inns. Through all these processes the bodyhas approached the adult stage ; it is quite evident that by the protrusion andrapid growth of the trunk, and the comparatively sl
Text-book of comparative anatomy . each side. These become the permanentnephridia of the adult Phoronis. The Actinotoocha thus formed sinks to the lioiiomof the sea ; the invaginated trunk protrudes and grows quickly, the mid-gut at thesame time entering it and forming a loop with ascending and descending whole prostomium, with the neural plate and the larval tentacles, are thrownoff and devoured by the young Phoi-inns. Through all these processes the bodyhas approached the adult stage ; it is quite evident that by the protrusion andrapid growth of the trunk, and the comparatively slight growth of the rest of theoriginal larval body, the anus comes to lie dorsally near the mouth. This processreadily allows of being referred back to the similar process in Sijitniculus, only theretin- rudiment of the trunk is never invaginated into the larval body. Brachiopoda.—The free-swimming larva of Argiope, (Fig. 183) consists of threeconsecutive divisions, which are called the anterior, middle, and posterior B FIG. iss.—A, free - swimming, H,attached larva of Argiope, fromalxivi- (after Kowalewsky). vs, An-terior segment; ms, middle segment;hs, posterior segment; ?«, mantle;md, mid-gut; wk, ciliated organ. m tSU en Rd
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanatomycomparative
