. A textbook of invertebrate morphology [microform]. Invertebrates; Morphology (Animals); Invertébrés; Morphologie (Animaux). 206 INVEliTEBHATE MOliPUOLOGY. the urea ouclosed by the lopliophore. The nervous system is exceediuf^ly simple, cousistiug of a siugle gaugliouic mass (Figs. 114 and 115, ce) lyiug betweeu the mouth aud auus, nerves ramifying from it to the various parts of the body. The only sense-organs that have been detected are situated upon the free portions of the body, more especially on the lophophoral tentacles {t), aud are represented by scattered ectodermal cells each of whi
. A textbook of invertebrate morphology [microform]. Invertebrates; Morphology (Animals); Invertébrés; Morphologie (Animaux). 206 INVEliTEBHATE MOliPUOLOGY. the urea ouclosed by the lopliophore. The nervous system is exceediuf^ly simple, cousistiug of a siugle gaugliouic mass (Figs. 114 and 115, ce) lyiug betweeu the mouth aud auus, nerves ramifying from it to the various parts of the body. The only sense-organs that have been detected are situated upon the free portions of the body, more especially on the lophophoral tentacles {t), aud are represented by scattered ectodermal cells each of which bears a strong cilium aud is in connection with a nerve-iibre; they have been assigned a tactile function, though it seems probable that they react to stimuli of various kinds and have a much more generalized function. The arrangement of the excretory and reprodnctive organs varies considerably in different forms and may be more con- veniently described in connection with the various orders. 1. Order Endoprocta. This order contains but a small number of forms, which, with one exception, Urnatella, are marine in habitat. They all possess the power of reproducing by budding, colonies being thus formed, as in Pedicellinay Ascopodaria, and other genera with the exception of Loxosoma, in which the buds separate completely from the parent at a relatively early stage of their development. Each in- dividual (Fig. 114) is a cup-shaped structure, prolonged posteriorly into a stalk (d) and upon the rim of the cup, which represents the lophophoral fold, or slightly below it on the inner Fig. iNm- surface, the tentacles (<) are arranged viDUAL OF PedieeUina in a circle surrounding a depression, the vestibule, into which open both the mouth and the anus, the situation of the latter opening within the circle of tentacles having suggested the name given to the order. The tentacles can be coiled in a circinate manner, so as to lie completely /t —. (after Nitsche). ee = gang
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