ACALEPH^E. 123 



Sp. Geryonia proboscidalis, Medusa proboscidalis FORSK. Icon, rer. not. Tab. 

 36, fig. i ; GUERIN Iconogr., Zooph. PI. 16, fig. i ; CUVIER, R. Anim., edit, 

 illustr., Zooph., PI. 52, fig. 3. This species from the Mediterranean, with 

 six threads or tentacles at the margin of the disc, may be considered as 

 the type of this division. 



Family VII. Ehizostomidce. Arms ramose, with many suc- 

 torial oseules. Margin of the body without tentacles. Disc with 

 four ovaria or testes, sometimes (in Cassiopea) eight. 



Rhizostoma Cuv. Tentacles amongst the arms none; arms 

 confluent into one pedicle inserted in the disc. 



Sp. Rhizostoma Cuvierii, REAUMUR Mem. de VAcad. des sc. de Paris, 1710, 

 PI. xi. fig. 27, 28 ; CUVIER Journ. de Physique Tom. XLIX. p. 436; Cuv. 

 R. Anim. edit. ill. Zooph. PI. 49. This species sometimes attains to 

 a great size. The Rhizostoma has four pairs of suctorial arms, which are 

 provided with absorbent vessels ; by these it receives its nutriment, which 

 consequently consists of minute animalcules, or of animal matters in 

 solution. These absorbent vessels and their branches coalesce into four 

 stems, which run along the pedicle and end in the stomach. From the 

 stomach run laterally vessels through the hood. Surrounding the stomach 

 are four cavities, with very wide opening below, in which the organs 

 of propagation are seated. The uppermost portion of the hood consists of 

 a substance more firm than the rest of the body. See K. W. EYSENHARDT, 

 Zur Anatomic und Naturgeschichte der Quatten, Nov. Act. Acad. Cces. 

 Leop. Carol. Nat. Curios. T. x. pp. 375, &c. with figures. Rhizostoma 

 Aldrovandi PE'RON, GUERIN Iconogr. , Zooph. PI. 15, fig. i, &c. 



Cassiopea PERON. Tentacles amongst the arms none. Arms 

 eight or ten, very much branched, not conjoined at the base into a 

 peduncle, furnished with vesicular appendages. 



Sp. Cassiopea frondosa, Medusa frondosa PALL., Spic. Zool. x. Tab. II. fig. 

 i 3 ; Cassiopea borbonica DELLE CHIAJE, Memorie sulla storia e notomia 

 degli Animali senza vertebre del Regno di Napoli, I. 1823. Tab. in. ; GUERIN 

 Icon. Zooph., PI. 15, fig. 2 ; Cuv. R. Anim. edit, illustr., Zooph. PI. 51, 

 fig. 2, &c. (See other figures of TILESIUS Nov. Act. Acad. Cces. Leop. Car. 

 Natur. Curios. Tom. XV. 2. 1831, pp. 247 288, Tab. 69 73. 



Cephea PERON. Large cirri amongst the arms. 



Sp. Cephea cyclophora PERON. Medusa cephea FORSK. Icon. rer. not. Tab. 

 xxix. fig. (copied in Cuv. R. Anim. edit, illustr., Zooph. PI. 51, fig. 4) &c, 



B) Mouth single central. 



Family VIII. Medusidea. Mouth tetragonal central. Arms 

 four, mostly very distinct, very rarely none. Four lateral cavities 

 in the disc, open beneath, inclosing the genital organs. 



