424 Miscellaneous. 



tubes. Iu general the external tubes are more slender, but longer 

 than the internal ones. 



M. Bertkau has in vain sought for these simple tracheae at the 

 extremity of the abdomen in Oletera, Dy sclera, and Segestria. 



Thus it is established that the Araneida have four stigmata, of 

 which the two anterior are situated at the anterior part of the ab- 

 domen. The two others are placed either immediately behind these 

 or further back, at the extremity of the abdomen. In this latter case 

 they unite to form a fissure in the median line. The first pair of 

 stigmata always leads to " lungs ;" the second to lungs (Mygalidae) 

 or, more frequently, to tracheae. When the second pair of stigmata 

 is anterior, the tracheae to which it corresponds always present two 

 principal trunks — one directed forward, furnishing trachean tubes 

 to the cephalothorax {Dysdera and Segestria), whilst the other 

 passes backward and supplies the abdomen. When the second 

 pair of stigmata is situated at the extremity of the abdomen, and 

 the two trunks must necessarily go forward, it is the external 

 one which corresponds to the posterior trunk of Dysdera and 

 Segestria. 



The modifications which are observed in the respiratory apparatus 

 of the Araneida are in correlation with those which are manifested 

 in the rest of the organization and which have served to establish 

 the principal groups. There are, however, some points on which a . 

 division having for base the organization of the respiratory apparatus 

 does not exactly coincide with the classification adopted now. This 

 is observed, for example, in the family of the Thomisidae, in which 

 the genera Thomisus, Xysticus, Artamus, and Philoclromus have 

 ramified trachean tubes, while they are not so in Sparassvs and 

 Thanalus. But it must be remarked at the same time that the 

 forms belonging to these two genera differ by their facies, by the 

 claw of their first jaws, and by the claws of the feet. M. Bertkau 

 has therefore established a family of Sparassidae which forms a trans- 

 ition from the Thomisidae to the Lycosidae. Scytocles includes the 

 only known representatives of a new family, that of the Scytodidoe ; 

 and Dictyna, Erigone, and Micryphantes constitute the family of the 

 Micryphantidae, in which, perhaps, we ought to place Argyroneta, a 

 genus of which the place is yet uncertain. 



The author proposes the following grouping of the Araneida : — 

 1. Two pairs of laminar tracheae. Mygaliclce (Tetrapneumones). 

 II. A single pair of laminar tracheae. 



A. A pair of tubular tracheae in tufts. 



a. Stigmata distinct. Dysdera, Arcjyroneta. 



b. Stigmatary aperture common. Micryphand e , Attidce. 



B. A pair of ramified tubular tracheae with a common orifice. 

 Thomisidae. 



C. Four simple tubes with a common orifice. Scytodidce, Drassidce, 

 Agelenidce (excl. Argyroneta), Epeiridce, Therididte (in great 

 part), Sparassidce, Lycosidce. 



— Archiv fur Naturg. vol. xxxviii. (1872) p. 208 ; Bill. Univ. 

 April 15, 1873, Bull. Sci. p. 355. 



