I02 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 



,-f . -,,. V . - . , Lucemaria auricula ;• 



(Lucernaria, rig. 13), or m the intervals/, disc of attachment; 



/, body ; m, mouth ; «, 



between the angles (Depastrum) of the <^i"ster of suctorial ten- 



•-^ ^ -^ ' tacles ; ;•, generative 



octagonal disc ; or the margin may be elements. 

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

 duella, Calycinaria). There are wide radial canals 

 passing from the marginal suckers to the stomach. 

 The reproductive elements arise in these tubes, ex- 

 tending to the edge in Depastrum and Lucernaria, 

 not in Carduella. Development is direct. They live 

 in the N. Atlantic Ocean. 



CHAPTER XVT. 



HYDROZOA, 



Sub-class 4. 'D\sco-ph.or2i[Eschscholtz). — Free, oceanic 

 forms, with a basal u?Tibrcllay\\\nch. 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. 



