284 Miscellaneous. 



mal has no other motions than those which are given it by the 

 agitation of the liquid. During this period, small buds are distin- 

 guished, arranged in regular rows around the oral pole. Towards 

 the twentieth day spiniform processes are developed on the top of 

 these buds, of a great length in comparison to the bulk of the ani- 

 mal. The calcareous matter already enters so largely into their 

 composition, that the least shock is sufficient to break them without 

 making them bend. 



I have followed the progress of the animal up to the moment when 

 it is detached from its pedicle, doubtless to live under the form which 

 it retains during the rest of its existence. However incomplete may 

 be my observations, I think that they may give a general idea of the 

 development of the Echinus, and allow us to draw from them the fol- 

 lowing deductions : — From the moment when the embryo has a form 

 of its own, all the parts of its body are arranged almost symmetri- 

 cally around the bucco-anal axis, and, consequently, it bears in the 

 highest degree all the characters of the type of the zoological class 

 in which it is arranged, that is to say, of the radiate type. 



It is around the bucco-anal axis that the activity of the genesic 

 process is manifested from its origin, and is maintained greater 

 during the whole course of the development ; and it is principally 

 from the two extremities of this axis that it radiates, and extends 

 gradually to the other parts of the tegumeutary envelope. 



Search as much as we may, in the arrangement of the different 

 parts of the Echinus esculentus, for a tendency to bilateral develop- 

 ment similar to that pointed out by M. Sars in an Asteria, not the 

 least trace will be found, even during the shortest duration of one of 

 the phases of the genesic phsenomena. In the larva of the Echinus, 

 when the body elongates as well as when it contracts, to return to 

 nearly its primitive configuration, these changes take place in the 

 direction of the bucco-anal axis, so that the radiate form is not at 

 all affected by it. In short, as soon as we can discover the first 

 organic lineaments of this being, it is already a radiate embryo, and 

 the animal, in all the other phases of its life, remains invariably ra- 

 diate, — Comptes Rendus, Jan. 4, 1847. 



Remarks on Opalina Na'idos, an Entozoon found in the Naiadae. 

 By Dr. O. Schmidt. 



The very interesting discovery of this entozoon was made in a 

 species of Ndis nearly allied to N. elinguis, which is furnished with 

 a bundle of hooks at each fourth hook. When the Naid lies upon 

 its side, a spot in which the oral fissure appears as a notch and the 

 ciliary motion in the oesophageal bulb may be very distinctly per- 

 ceived. I was looking for the fleshy ridges, which in Stylaria 1 

 correctly considered to be regarded as forming the tongue, and was 

 delighted on perceiving that a somewhat elongated body situated in 

 the oesophageal bulb, and M^hich was pointed anteriorly, frequently 

 moved nearly as far as the oral fissure, and then, as it appeared to 

 me, was again retracted. I had not expected to find so moveable a 



