ARACHNIDA. 



ABANE2E. 



A comprehensive work ' Ueber die Lebensweise der Arach- 

 niden' (On the Habits of the Araclmida,) by A. Menge, 

 has been inserted in the ' Neuesten Schriften der Naturf. 

 Gesellsch. in Dantzig' (i Bd. 1 Hft.) 



This memoir includes (1) The Development. Previous to the first change 

 of integument the young Spiders are naked, of indeterminate colour, and 

 remain as it were torpid, at the place of birth ; but, after the change of 

 skin, they become hairy, of determinate colour, and active, and it is not till 

 then also that the spinnerets are developed. The later changes have refer- 

 ence only to size, colour, form of abdomen, and, in the male, to the shape of the 

 palpi. (2) Habitation. (3.) Movement. Interesting relations of the formation 

 of the foot to the mode of progression. (4-) Nutrition. This section also 

 contains anatomical discoveries of great importance, especially on the respi- 

 ratory organs. The author having been successful in discovering, in Aryy- 

 roneta, trachese, together with pulmonary sacs, which he has here particularly 

 described and figured, he sought for them also in other Spiders, and met 

 with them in Salticus and Micryphantes, but not in Epeira, Tegenaria, 

 Lhiyphia, Lycosa, and Thomisus. The tracheae of Salticus and Micryphantes 

 open at the extremity of the abdomen, near the spinnerets, and lie in tufts 

 or clusters in the abdomen, to which they are always confined. (5) Con- 

 struction of the web. Instructive exposition of the procedure in the construc- 

 tion of the web in the various families. (6) Propagation. (A.) Copulatiou. 

 It was reserved for the author to solve the physiological enigma which this act 

 had hitherto presented. The spoon-shaped palpi of the males are in fact the 

 copulative organs, with which they take the semen from the appropriate open- 

 ings of the seminal ducts on the base of the abdomen, and transfer it to the 

 sexual opening of the female. The procedure is carefully described in various 

 Spiders. (B. ) Structure of the nest and care of the young. The 

 fertilized ova are deposited at several times. All Spiders surround their 

 ova with a web. In many species the young, after they have escaped from 

 the egg, are tended and even fed by the mother. (7) Autumnal migrations. 

 The author refers the phenomena of the so-called "flying Summer" (Gossa- 

 mer) to the circumstance that the Spiders which inhabit moist localities 

 resort to places more suitable for the winter, by means of the filaments 

 emitted from them. (8) Perceptive faculties. The author has not been 

 able to satisfy himself that sounds make any impression on Spiders. He is 

 also opposed to the general opinion that they are prescient of approaching 





