504- Proceedings of Philosophical Societies. [Oct. 



M. Geoffrey, la the work of which we have spoken, insists 

 more than usual upon these last relations, to which he thinks 

 sufficient attention has not been paid. He shows particularly 

 that the singular elongation of the anterior extremities, the 

 general tendency of the skin to become excessively wide, and 

 the peculiar properties which are the consequence of this in the 

 bats, both with respect to their sensations and motions, require 

 us to place these mammalia in a separate order ; while, at the 

 same time, their striking resemblance to the quadrumania, and 

 to the carnivorous animals, requires that this order should be 

 placed between them. We may look with interest to the sub- 

 division of this order, and to the history of the species, which 

 M. Geoffroyhas promised. 



M. de la Mark, employed at the Museum of Natural History 

 in teaching every thing which concerns the animals destitute of 

 vertebras, published, some years ago, the work which serves as a 

 basis to his course. He explains in it, according to his own 

 method, the classes, orders, and genera, of these numerous 

 animals: but as travellers have since discovered many genera 

 and species, as anatomists have more completely explained the 

 structure, and as the meditations of la Mark on the subject have 

 m:».de him discover various new relations among these animals, 

 he has published an abridged table of his course, after his me- 

 thod in its most perfect state, in which he satisfies himself with 

 giving the characters of the greater divisions, and simply enu- 

 merating the names of the genera. 



He follows in their arrangement the degrees of complicate- 

 ness, beginning with the most simple animals. Supposing that 

 those which have no visible nerves only move in consequence 

 of their irritability, he calls them apathic animals.. He gives 

 the name of sensible animals to the other animals without ver- 

 tebrae, and of intelligent animals to those which have vertebrae. 

 To his old classes, now well known to naturalists, he adds the 

 cirrkipeda, which include the glands -de-mer, and other ana- 

 logous animals, and which he places between his annelides and 

 his mollusca ; that of the epizoaines, or intestinal worms, which 

 he places among his apathic animals ; and the infusoria, or mi- 

 croscopic animals without visible mouth or intestines. He leaves 

 the pekinodermes in his radiaires, and among the apathic animals, 

 with a greater degree of simplicity than the intestinal worms. 

 We regret that we have not room to notice the other changes 

 introduced by M. de la Mark into his orders, nor the numerous 

 additions which he has made to the list of genera ; but natu- 

 ralists will not fail to look for them in the work itself. 



Notwithstanding the success of the anatomical investigations 

 of animals without vertebrae for several years back, there still 

 remained a family in which the fundamental organs were not 



