POLYZOA. 705 



this sub-class, Loxosoma and Pedicellina^. The body is more or less 

 cup-shaped, and affixed by its dorsal or convex surface to a contractile 

 flexible stem, which, in Loxosoma, is attached in turn to some foreign 

 object by an expanded foot, or sole, but, in Pedicellina, is continuous with 

 a branched stolon. This stolon usually creeps over other Polyzoa or 

 Hydrozoa. A diaphragm separates the body from the stalk in Pedicellina, 

 and the body frequently breaks off and is replaced by a successor, pro- 

 duced by budding from the stem. The foot of Loxosoma contains a foot- 

 gland perhaps homologous with the primitive shell-gland of Mollusca 2 . It 

 is always present in the young organism, and is retained in many species 

 by the adult. It appears to be represented in the larva of Pedicellina. 

 The rim of the cup, or body, i.e. the lophophore, is contractile, and can be 

 partially closed over the cavity of the cup or vestibule. Just within its 

 border is inserted a bilaterally symmetrical and single series of tentacles, 

 ciliated on their adoral surface, towards which they can be rolled up when 

 the animal is irritated or alarmed. A small lobe, or epistome, which 

 carries a tuft of cilia in the larva of Pedicellina, projects between mouth and 

 anus, both of which lie within the vestibule. The nervous system consists 

 of a single ganglion, placed transversely between the mouth and anus. It 

 gives off nerves to each of the tentacles and, in Loxosoma, to a pair of sen- 

 sory tubercles ( = the dorsal organ described below ?). The nerves terminate 

 in bipolar ganglion cells, one branch of which goes to an ectodermic sense 

 cell provided with a single sense-hair. In Loxosoma each tentacle-nerve has 

 a ganglion at the base of the tentacle. Sense cells are found on the aboral 

 surfaces of the tentacles and, in Loxosoma, numerously round the rim of the 

 vestibule, more sparsely elsewhere, and rarely on the stem. The intestine 

 is U-shaped, and consists of a stomodaeum and a mesenteron, the cells of 

 which contain pigment. There is a proctodaeum in Pedicellina, but in 

 Loxosoma it is possible that the blastopore persists as the anus. There is 

 no body cavity, but a gelatinous matrix with connective tissue cells and 

 muscle cells occupies the interval between the alimentary tract and body 

 walls. There are two nephridia with ciliated tubes which open on the 

 adoral side of the nerve ganglion, as in some Chaetopod Trochospheres 

 (Harmer). Testes and ovaries are both present, but appear to ripen at 



1 To these add : Ascopodaria, a marine undescribed form dredged by the ' Challenger/ with an 

 umbel of Pedicellina-\\kz zooids borne upon a stalk (Lankester, ' Polyzoa,' Encyclopaedia Brit, xix) ; 

 Urnatella gracilis, from the Schuykill river, U. S... a fresh-water form occurring in small colonies, 

 consisting of a disc of attachment bearing one to six stems with urn-shaped joints and more or less 

 branched, zooids like Pedicellina, dying at the end of the year, and stems persisting to bud the 

 following year (Leidy, Journal Acad. Nat. Sc. Philadelphia (2), ix. pt. i. 1884, and Proc. of same, 

 1884). Barentsia, with a chitin-covered creeping stolon, giving off stems with lateral zooids, is 

 supposed by Hincks (A. N. H. (5), vi. 1880) to belong here. Its full description by Vigelius 

 (Bijdrag tot de Dierkunde, xi. 1884) has been inaccessible to me. 



2 Or it may be a portion of the ciliated ring of the larva. See Harmer, Q. J. M. xxvii. (2), 

 1886, p. 250. 



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