Morphology and Phyloyeny of Insects. 433 



siderable attention has been bestowed upon the abdominal 

 appendages of Inseets by Dr. Ilaase, who recently published 

 a detailed treatise* upon this subjeet. Unfortunately 

 Dr. Haase's very interesting paper takes zoographical and 

 anatomical facts too exclusively into consideration ; it pays 

 but little attention to comparative embryology. In my 

 opinion, however, it is altogether impossible to set up homo- 

 logies without constant reference to the facts of embryology. 

 For instance, while Haase decides the question as to the 

 abdominal styles of MacJiilis and Campodeay which is alto- 

 gether in dispute, because it has not yet been embryologically 

 investigated, by declaring them to be coxal appendages, he 

 also assigns to the same category the so-called styli of the 

 Orthoptera, whilst partly appealing to my own investigations, 

 which are stated by him to show that the styli " only arise 

 from dermal papillai considerably later than the rudiments of 

 the legs, and even than those of the cerci." 1 am bound to 

 declare that neither from my figures f nor from my prepara- 

 tions, which were at his service, was it possible for Dr. Haase 

 to di-aw such a conclusion. The styli do not arise from 

 " dermal papillee/' but consist, like the rest of the extremi- 

 ties, of ectoderm and mesoderm, and their cavity communi- 

 cates with that of the somite to which they belong. More- 

 over, it is indeed true that they arise some time after the 

 thoracic legs, but not later than the cerci. The truth may 

 possibly be that for the earliest rudiments of the cerci Haase 

 mistook the caudal lobes, which subsequently undergo 

 degeneration and are almost entirely absorbed in the forma- 

 tion of the cerci, as has already been described by Tichomirow 

 in the case of Bombyx mori. The sole difference between the 

 styli and the cerci on the one hand, and the rest of the abdo- 

 minal appendages on the other, consists in the fact that the 

 latter soon disappear, while the former persist in post- 

 embryonic development. I have therefore no doubt that the 

 styli in Phyllodromia (and, as is highly probable, in all 

 Orthoptera) are genuine rudiments of limbs, and do not 

 correspond to the abdominal styles of Machilis and Ganipodea, 

 in the event of Haase's view as to the value of the latter as 

 coxal appendages being correct. 



It is true that with regard to the cerci certain doubts 



* Ilaase, " Die Abdoruinalanhiiuge der Insekten mit Beriicksichtung 

 der Mvriapodeu," Morphol. Jabibucher, J3d. xv., 188[), pp. 331-435, 

 Taf. 14, 15. 



t N. Cholodlcowsky, " Studien zur Entwicklungsgescliicbte der 

 Insekteu (n. Nachtrag dazu)," Zeitscbr. f. wiss. Zool. Bd. 48, pp. 89-100 

 and 301-302, Taf. viii. 



Ann. dc Mag. N. Hist. Ser. 6. Vol. x. 30 



