10 ON THE ANATOMY OF THE FAMILY OF THE MEDUSA 



steady), I never failed in procuring all the information I required. 

 The great matter is to obtain a good successive supply of specimens, as 

 the more delicate oceanic species are usually unfit for examination 

 within a few hours after they are taken. 



Section I. — Of the Anatomy of the Medusa. 



4. A fully-developed Medusa has the following parts : — i. A disc 

 2. Tentacles and vesicular bodies at the margins of this disc. 3. A 

 stomach and canals proceeding from it ; and 4. Generative organs, 

 either ovaria or testes. The tentacula vary in form and position in 

 different species, and may be absent ; the other organs are constantly 

 present in the adult animal. 



5. Three well-marked modifications of external structure result 

 from variations in the relative position of these organs. There is 

 either — ist, a simple stomach suspended from the centre of a more or 

 less bell-shaped disc, the disc being traversed by canals, on some part 

 of which the generative organs are situated, e.g. Geryonia, Thauman- 

 tias ; or 2ndly, a simple stomach suspended from the centre of a disc ; 

 but the generative organs are placed in cavities formed by the pushino- 

 in, as it were, of the stomachal wall, e.g. Aurelia, Phacellophora ; or 

 3rdly, the under surface cjf the disc is produced into four or more 

 pillars which divide and subdivide, the ultimate divisions supportinc^ 

 an immense number of small polype-like stomachs ; small apertures 

 lead from these into a system of canals which run through the pillars, 

 and finally open into a cavity placed under the disc ; the generative 

 organs are attached to the under wall of the cavity, e.g. Rhizostoma, 

 Cepliea. 



6. To avoid circumlocution I will make use of the following terms 

 (employed by Eschscholtz for another purpose) to designate these 

 three classes, viz. Cryptocarpa: for the first, Phanerocarpa; for the 

 second, and Rhizostomid.-e for the third. 



7. In describing the anatomy of the Medusae it will be found most 

 convenient to commence with the stomach, and trace the other organs 

 from it. 



Of the Stomach.— lYns organ varies extremely both in shape and 

 in size in the Cryptocarpas and Phanerocarps. But whatever its 

 appearance, it will be always found to be composed of two mem- 

 branes, an inner and an outer. These differ but little in structure • 

 both are cellular, but the inner is in general softer, less transparent' 

 and more richly ciliated, while it usually contains but few thread-cells' 

 The outer, on the other hand, is dense, transparent, and either dis' 



