. A text-book of invertebrate morphology. Invertebrates. TYPE PR080P70IA. 265 This vestibule is a deep depression of the oral surface of the larva, differing from that of the Pedicellina larva only in hav- ing an arch-like thickening of its walls (only one side of the arch is represented in the figure) which imperfectly separates an oral portion of the vestibule from a posterior or anal portion, a glandular depression situated in the roof of this latter portion constituting the adhesive organ {ad). In front of the oral vestibule is situated a ciliated depression from which projects a tuft of l
. A text-book of invertebrate morphology. Invertebrates. TYPE PR080P70IA. 265 This vestibule is a deep depression of the oral surface of the larva, differing from that of the Pedicellina larva only in hav- ing an arch-like thickening of its walls (only one side of the arch is represented in the figure) which imperfectly separates an oral portion of the vestibule from a posterior or anal portion, a glandular depression situated in the roof of this latter portion constituting the adhesive organ {ad). In front of the oral vestibule is situated a ciliated depression from which projects a tuft of long cilia and which appears to correspond to the cement-gland of the Pedicellina larva and to a glandular structure in the more modified Ectoprocta larvae, known as the pyriform organ (pyr), by which name it may be known here. The similarity of this larva to that of Fedicellina is clear, the details of organization of the two forms agreeing part for part; in other Ectoprocta, however, great differences are to be found. In the genus Bugula, for exam- ple, the larva (Fig. 118) is a barrel-shaped organism at the one extremity of which is a thickening, the calotte {cal), which appears to correspond, in part at any rate, to the apical thickening or dorsal organ, as it is sometimes termed, of Pedicel- lina and Gyphonautes. The sides of the barrel are formed by a circle of elongated cells forming the corona and equivalent to the marginal corona of the other larvse; it does not, however, form a simple band in Bugula, but its cells are much shorter on one of the faces of the embryo than elsewhere, producing a well-marked groove at the apex of which lies the pyriform organ {pyr) whose homologies in Gyphonautes have already been pointed out. A peculiarity of this larva is the entire absence of a digestive tract, the lower end of the barrel being occupied by a depression, the adhesive organ {ad). Between such a larva as that just described, entirely des- titute of a digestive tract, and th
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyo, bookyear1894
