POLYZOA. 
73 
with a zone of air cells, and with hooked spines, the total diameter 
being about ^ of an inch. 
Sub-class II.— Entoprocta. 
In this small group, both orifices of the alimentary canal open 
within the circle of tentacles, and there is no tentacular sheath. 
The polypides are borne on contractile stalks. In the Pedicel- 
UnidcB the stalks arise from a creeping stolon. In Pedicellina cernua * 
(Fig. 24) a stolon, creeping over sea-weeds, etc., gives rise to stalked 
cups, the movements of which are vigorous : " the polypides, when 
excited, dash themselves vehemently from side to side. The heads 
Table 
Case A, 
upright 
part. 
Pedicellina cernua. x 27. 
[' The Cambridge Natural History.'] 
are easily knocked off, but the decapitated stalks develop fresh ones. 
In Ascopodaria the stalks are swollen at the base ; A.fruticosa*, from 
Port Phillip, Victoria, forms beautiful tree-like colonies. The 
Loxosomidce do not form colonies, owing to the buds becoming 
detached from the parent. The species of Loxosoma are always found 
associated with some other animal, such as a worm or Tunicate. 
The tentacles of the polypide are arranged obliquely to the long 
axis of the body, hence the name of the family (loxos, oblique). 
Loxosoma phascolosomatum * occurs, in the form of delicate tufts, on 
the caudal end of the Sipunculid worm Phascolosoma. The individuals 
resemble pins with little white heads, and are capable of vigorous 
movements to and fro ; occasionally a stalk coils itself up into a 
spiral. 
