ACALEPH.^. 169 



under a certain range of modifications in tlie Acalephaa, I have 

 proposed the definite term of " cjsticle " *, I may remark that Gaede 

 first described, in Medusa aurita, eight of these bodies in the margin 

 of the disc, Avhich to the naked eye appear as white points, but under 

 the microscope are seen to be hollow bodies containing at their 

 free end minute corpuscles f, the uppermost of -which are grayish, 

 the undermost brownish, and all of them more or less hexan- 

 gular. Ehrenberg compares these corpuscles with the crystals of 

 quartz, but found them, contrary to Rosenthal's statement, soluble 

 and effervescent in sulphuric acid. Observing a little cell filled with 

 red pigment granules above each cysticle in the CyancBci auricula, 

 the same eminent micrographer suggested that they might be organs 

 of vision analogous to the ocelli or coloured specks in Rotifera and 

 Entomostraca.\ 



In all the larger Medusos which are characterised by a much rami- 

 fied and anastomosing series cf chylaqueous vessels the cysticles are 

 protected by more or less complicated membranous hoods or lobed 

 coverings : in the smaller Medusee which possess a more simple 

 chylaqueous system, the radiating canals of which are either 

 unbranched, or if ramified, not anastomosing, the cysticles are 

 unprotected, exposed, and often obsolete. Prof. E. Forbes, adopting 

 Ehrenberg's idea of their function, proposes to divide the Pul- 

 mogrades into the Steganopthalraata and Gymnopthalmata. In the 

 latter or bare-eyed family the pigment-cells associated with the 

 cysticles vary much in colour, being purple, orange, yellow, black 



* Hohlen KiJrper mit Kdrperchen, Gaede. Rand Korpern und Auge, Ehrenberg. 

 Tubercules vesiculaires, Edwards. Geho/blaschen, Will. Gehorwerkzeuge, Siebold. 

 In the excellent monograph, CXLV., they are called, in paragrajjh 21, "marginal 

 corpnscles," in the next paragraph " marginal vesicles ; " in par. 22 " the cor- 

 puscle " simply. In the description of the plates, " fig. 8. is a portion of the 

 marginal canal, with a tentacle, and two marginal corpuscles. Fig. 9. portion of 

 the marginal canal, with a young tentacle, and a marginal vesicle, containing iwo 

 corpuscles." (p. 431), the same name being sometimes applied to the contents, and 

 sometimes to the thing containing, or to the whole organ. One so zealous for the 

 right understanding of the structures of the marine invertebrata, as the clear- 

 sighted author of CXLV., will be the first to excuse the attempt to remove a 

 source of ambiguity in any detail of their descriptive anatomy. I have proposed 

 for the constant and remarkable organ in question, the term " cysticle" (from ci/sti- 

 cula), instead of cysticule, agreeably with the analogy of " tentacle," and " pe- 

 duncle," applied to other parts of the Acalephce. This single-worded name has 

 also the advantage of suggesting no hypothetical view of function. 



t " Unter dem mikroskop aber wird mann einen hohlen Korper gewahr, der an 

 dem einen freien Ende viele kleine Korperchen tragt." CXXXIX. p. 1 8. 



; CXLI. p. 574, 575. 



