222 CONTRIBUTIONS TO THE NATURAL HISTORY 



A new-comer into tlie field of these researches, after having spent the best of my 

 earlier years in other labors, and happy to find still something to glean where Peron 

 and Lesueur, Cuvier, Esclischoltz, Ehrenberg, Milne-Edwards, Mertens, Brandt, Lesson, 

 Sars, Loren, Steenstrup, Von Siebold, Dnjardin, Will, Edward Forbes, Sir John Dal- 

 yell, and others, have reaped full harvests, I have not the pretension to offer any thing 

 very complete upon this subject. 



Three years of study on the sea-borders have hardly yet fully opened my eyes to its 

 inexhaustible treasures. I bring only some loose fragments respecting several jjoints of 

 the structure of Medusae, before unknown or little understood, Avhich I have attempt- 

 ed to clear up, as far as it has been in my power. 



In the illustration of the objects which I am about to describe, I have been largely 

 assisted by the ability of Mr. Sonrel, whose quickness in seizing the characteristic fea- 

 tures of organized beings, and in reproducing them with a delicate touch, I have already 

 had opportunities to appreciate, during the publication of my researches upon the fossil 

 fishes, and those of the fresh waters of Europe, and also upon the Echinodermata and 

 shells. All the illustrations of Medusje which I now publish are drawn, as well as en- 

 graved, by his hand. The part which he has taken in this work is so important, that, I 

 am happy to acknowledge, without his aid, I should have been unable to reproduce, or, at 

 least, to make equally intelligible to others, the facts which I had ascertained. 



Some of the numerous figures which I have caused to be engraved may appear 

 rather superfluous. But it must be considered that these animals are so perishable, that 

 it will hardly ever be possible to preserve extensive series of them in our museums, or to 

 procure of those capable of preservation a sufficient number to represent them in their 

 different attitudes and under various circumstances, so as fully to illustrate all the details 

 of their structure. For, though entire specimens of the smaller species may be pre- 

 served in Goadby's liquid with tolerable success, yet details which may be traced in the 

 fresh state are almost always lost soon after. Moreover, they have to be traced under 

 rather high magnifying powers, and for some details the highest powers at our conuiiand 

 . are hardly sufficient for the investigation. It must be obvious, therefore, that full original 

 illustrations of as many of these animals as can be obtained will be always of service to 

 the progress of science, and should at once be secured whenever the opportunity offers of 

 investigating the new forms which fall within our reach ; especially when we consider 

 that, in many cases, opportunities may not be afforded for years again to investigate the 

 same subject in the same state. 



I should mention, also, some advantages I have derived from availing myself of various 

 methods of proceeding in studying these animals. While many details of structure can 



