348 



ZOOLOGY 



s I:CT. 



of each zooid from the stalk. Gunopodaria ramosa has a branching 

 stalk. Urnatella has a disc of attachment with one to six, jointed, 

 branching stems. In Loxosoma, which is found attached to 

 various Annulata, two parts are distinguishable the calyx or body 

 and the stalk. In the base of the latter is the so-called foot-gland, 

 consisting of a small number of granular cells arranged around a 

 central space opening on the exterior. Buds are formed, but 

 become detached before reaching maturity. Segmentation of the 

 ovum is complete, and a gastrula is formed by invagination. 



Certain differences in the larval history have sometimes been 

 regarded as separating very widely the Endoprocta from the 

 Ectoprocta. The former, like the latter, have a free-swimming 

 ciliated larva, provided with a corona and a ciliated disc. This 

 develops directly into the primary zooid after becoming attached 

 by means of the oral surface. The ectoproct larva also, as stated 

 previously (p. 346), becomes attached by the oral 

 surface ; but any rudiments of a zooid such 

 as an alimentary canal which may have been 

 developed, become absorbed, and the primary 

 zooid is developed at the free or aboral end of 

 the larva, with its oral surface directed up- 

 wards, away from the base of attachment. 

 The difference, however, is not so important as 

 it may at first appear, for the parts of the larval 

 Endoproct do not remain in the reversed position 

 in which they are situated when attachment first 

 takes place, with the vestibule, mouth, and anus 

 directed downwards. Very soon a rotation is 

 observed to take place, by virtue of which the 

 vestibule and developing tentacles, with the 

 mouth and anus, become carried to their 

 permanent position on the free surface of the 

 animal. 



CLASS II. PHORONIDA. 



The position of Phoronis and its close ally, 

 Phoronopsis, worm-like marine animals, is a 

 matter on which widely divergent views are held. 

 On account of certain strong resemblances to the 

 Polyzoa, and, more particularly, to the Phylac- 

 tolaemata they are most commonly looked upon 

 as related to that class and to the Brachiopoda, 

 and the Phoronida may thus conveniently be 

 dealt with as a class of the Molluscoida. 



Phoronis (Fig. 289) lives in associations con- 

 FIG. 289. Fhoronis sisting of a number of individuals. These are 



auBtralis, natural uguallv J ooked upon ag naymg all been deve _ 



