MEDUSID^. 169 



peduncle or base of the brown body up to the head. I have lound 

 that each of these small brown bodies presents a very distinct red 

 point placed on the dorsal face of the yellow head ; and when I 

 compare this with my other observations of similar red points in 

 other animals, I find that they greatly resemble the eyes of the Rotifera 

 and Entomostraca. The bifurcating body placed at the base of the 

 brown spot appears to be a nervous ganglion, and its branches may 

 be regarded as optic nerves. Each pedunculated eye presents upon 

 its lower face a small yellow sac, in which are found, in greater or 

 smaller numbers, small crj'stalline bodies clear as water." The 

 presence of a red pigment in very fine grains is an argument in favour 

 of the existence of visual organs in these creatures, for the small 

 crystals disseminated in the interior of the organ would no doubt 

 perform the part of refracting light which is produced by the 

 crystalline lens in the eyes of vertebrated animals. Moreover, it is 

 found that there are marginal corpuscles analogous to these brown 

 spots in other species of Medusae. They are of a palish yellow, or 

 quite colourless, and enclose sometimes a single, sometimes many 

 calcareous corpuscles. When they are colourless, some naturalists 

 have rather taken them for organs of hearing reduced to their most 

 simple expression. 



The Medusae are not, according to Agassiz, absolutely destitute 

 of nervous system, ^\'e have seen that they may have ganglions, 

 and probably optic nerves. Ehrenberg also states that these have 

 ganglions at their base, which furnish them with nervous filaments. 



Without entering further into the details of their delicate and 

 complicated structure, we shall pause briefly on their mode of repro- 

 duction. We shall find here physiological phenomena so remarkable 

 as to appear incredible, had not the researches of modern naturalists 

 placed the facts beyond all doubt. "Which of us," says M. de 

 Quatrefages, "would not proclaim the prodigy, if he saw a reptile 

 issue from an egg laid in his court-yard, which afterwards gave birth 

 to an indefinite number of fishes and birds ? Well, the generation 

 of the Medusae is at least as marvellous as the fact which we have 

 imagined." Let us note, for example, what takes place with the 

 Rose Aurelia, a beautiful Medusa, of a pale rose colour, with nearly 

 hemispherical disc, from four to five inches in diameter, whose edge 

 is furnished with short russet-brown tentacles ; taking for our guide 

 the eloquent and learned author of " Metamorphoses in Man and the 

 Lower Animals," M. de Quatrefages. 



The Medusa designated under the name of Rose Aurelia lays 

 eggs which are characterised by the existence of three concentric 



