204 FOURTH IlEPORT 1834. 



foundation for a natural distribution of the genera In this exten- 

 sive family. Latreille has adopted it in the second edition of the 

 R^gne Anifmal, as he had previously done in his Families JVatu- 

 relles. It must be observed, however, that Walckenaer does not 

 attach so much importance to this modification of the respira- 

 tory organs. He states that it is not accompanied by anj^ cor- 

 responding differences in other parts of the structure, and that, 

 taken as the basis of a division, it leads to the separation of cer- 

 tain genera which, according to his views, are connected by the 

 closest affinity. Besides the above memoirs on the structure of 

 the Aranece, Leon-Dufour has published several others descrip- 

 tive of new or ill- understood species*. He has particularly 

 attended to the species found in Spain, as well as to the species 

 of Phalangium met with in the same countryf. He has dis- 

 covered a new method of preserving the Arane(s\, which it is 

 to be hoped may induce fresh labourers to enter upon this field. 

 It is greatly owing to the difficulty which has been hitherto 

 experienced in preventing the changes which occur after death 

 in these animals, that they have been so much neglected by 

 naturalists. 



De Hahn is the author of a work now in course of publication, 

 the object of which is to illustrate by coloured plates the genera 

 and principal species of this family§. Mr. Blackwall has pub- 

 lished some important memoirs on subjects connected with the 

 structure and oeconomy of the Araneidce\\, as well as others de- 

 scriptive of some undescribed genera and species^. 



Before leaving this class it may be mentioned that in the third 

 volume of the Zoological Miscellany** , Dr. Leach has published 

 an article on the characters of the genera of the family Scorpi- 

 onidcB, accompanied by descriptions and coloured representations 

 of all the British species of Chelifer and Obisiiim. Some ad- 

 ditions to these genera by Tlieis will be found in the Ann. des 

 Sci. for 1832t-i-. 



4. Myriapoila. — There can be no doubt that a certain affinity 

 exists between this class and the Annelida, as Latreille was the 

 first to point out in a memoir on the articulated animals pub- 

 lished in 1820:J:|. The Myriapoda have not been much attended 

 to. In the third volume of the Zoolog. Miscell. is a valuable 

 paper by Dr. Leach on these animals, in which he has given the 



• Ann. des Sci. Phys., torn. iv. Ann. des Sci. Nat., tomes ii. and torn. xxii. 

 f Ann. des Sci. Nat., torn. xxii. + Id. 



§ Die Arackiiiden getreu nacli der Natur ahgebildet und besehriehen, von 

 C. W. Hahn, 1831, &c. || Linn. Trans., vols. xv. andxvi. 



^ Land, and Edinb. PJiil. Mug. and Journ., J 83.3, vol. iii. 

 »* p. 48. t+ toni- xxvii. p. 57. %% Mem. du Mus., torn. vi. p. 116. 



