102 Introduction to Animal Morphology. 



has a body like an inverted bell, with a medial, square 



mouth on a projecting proboscis or hypostome. This 



bell is fixed on a pillar, and can detach Fig. 13. 



its aboral disc, and creep by its suckers, 



or swim like a Discophoran. The 



body cavity is four-chambered. At 



the margins of the disc are often litho- 



cysts and clusters of tentacles, either 



suctorial, adhesive, or similar to those 



of Medusae, placed on the angles 



/T . Lucernaria aurical* | 



Lucernaria. r if. i ^ 1, or in the intervals/, disc ot attachment; 



. mouth; ;/, 



between the angles (Depastrum) of th- ai ten- 



tacles; >, geaerattva 

 octagonal disc ; or the margin may be elements. 



entire, with the tentacles in several (1-3) rows (Car- 

 dud la, Calycinaria). There are wide radial canals 

 passing from the marginal suckers to the stomach. 

 The reproductive elements arise in these tube-, 

 tending to the edge in Depastrum and Lucernaria, 

 not in Carduella. Development is direct. They live 

 in the N. Atlantic Ocean. 



CHAPTER XVI. 



IIYDROZOA. 



SUB-CLASS 4. Discophora.(EsckscJwltz). Free, oceanic 

 forms, with a basal umbrella, which is not a mesothecal 

 expansion of the base of a manubrium, and has no 

 velum, but is traversed by not fewer than eight 

 branching, anastomosing canals, and bears sense- 

 organs in marginal notches (Fig. 14). Reproductive 

 organs in symmetrical pouch-like dilatations of the 

 body cavity. 



