Invertebrata. Zoological Collections, 



The Planari(B lactecB always fix their eggs to some solid body. Left to 

 themselves, they deposit them in dark places free from currents, in cavities, 

 and even in the mud. These eggs are not supported by a pedicle. 



Each individual may lay more than once in the spring, without being 

 fecundated anew after the first laying. The interval which occurs between 

 the two layings is five days, unless the animal has in the interval been 

 provided with abundant nourishment. 



The artificial expulsion of the egg is difficult when it is not the time, or 

 near being so ; but when it is ripe, or nearly so, it is very easy, and takes 

 place suddenly. 



The appearance of the foetus takes place twenty days after the laying, 

 according to the only strict observation M. Desmoulins was able to make 

 on this subject. The first young planaria which he saw, appeared towards 

 the 15th of March, whence it might be inferred, that the commencement of 

 the general laying took place from the 20th to the 25th of February. It 

 must be remarked, that the winter of 1829 was excessively long and severe. 

 In ordinary weather, the laying may probably commence about the 15th of 

 February, or even sooner. * 



The e^Q contains from ten to fifteen foetus Actes de la Soc. Linn, de 



Bordeaux, iv. 109. June, 1830. 



MM. Audouin and Milne Edwards on the Annelides and Mollusca These 



indefatigable naturalists have laid before the Academy of Sciences three 

 extended memoirs on the invertebral animals of the coast of France. 



The first, which is entitled " A Classification and Description of the 

 Annelides of France," forms a manuscript volume of nearly 400 pages, and 

 is accompanied by many plates, some of which are engraved, and ready to 

 : appear. 



"The second treats particularly of the bristles of these animals, considered 

 as organs of defence. Of this memoir we gave an analysis in our last 

 number, p. 176. 



The third, which contains the general results of their investigations, 

 exposes, in a summary way, several new facts relative to the anatomy of 

 the Crustacea, and the discovery of many new species of annelides and 

 mollusca. 



1. Annelides. In the part of this memoir devoted to the annelides, the 

 authors have described a new species of Siphonostoma, from the coast of 

 France, whose feet are provided with hooked bristles like those of the 

 TubicolcB, a circumstance which supports the opinions previously advanced by 

 these naturalists on the place which this genus ought to occupy in the systems. 

 The structure and habits of one of the unpublished species of Cli/mene, 

 discovered by them, establish new relations between this genus and Lumbricus, 

 in proximity to which they had placed it, whilst M. Savigny included it 

 ■ amongst the Tuhicolce. 



The habits of the annelides have hitherto been little attended to. MM. 

 Audouin and Milne Edwards have observed many interesting facts on this 

 subject. They have shewn that the Nephthys, Aricice, Glycerce, CirratuU, 

 Aglaurce, and several Eunicce, live buried in the mud or sand, like the 

 Arenicola ; and they have described the mode in which these animals form 

 their subterranean habitations. They have explained how certain Sahellce 

 change their place by means of the long tentacula which surround the 



* We have within these iew days met with a great number of the ova of the Planaria 

 lactea, in various states of perfection, at the bottom of the Glasgow Canal, wlxich was in 

 part laid dry during repairs. The eggs were attached to the under surface of stones, and 

 were also to be seen in several instances passing out from the body of the mother. We hope 

 shortly to be able, in conjunction with our coadjutor, Dr Scouler, Professor of Natural 

 History in the Andersonian University, to lay before our readers the results of our 

 observations on the development of these animals from the egg. — Eu. 



