Moiyhohgy and Phyhgeny of Insects. 431 



higlily interesting facts communicated by Carri^re are unfor- 

 tunately stated only too briefly ; besides this, his figures are 

 somewhat indistinct, and, what is especially to be regretted, 

 his paper contains no transverse sections from the cephalic 

 region such as would make it clear how the seven pairs of 

 ganglia, to which the author alludes, are related to the 

 cephalic extremities. Carribre considers the ganglion frontale 

 to be the nerve-centre of the first (foremost) cephalic seg- 

 ment ; as I have already stated, I do not think it possible to 

 liomologize the sympathetic ganglia with the centres of the 

 central nervous system. It is further to be remarked that, 

 according to Carri^re, the antennary segment is pre-oral, 

 Avhich, however, does not harmonize with his own figures. 

 Carrifere states that four pre-oral segments are present, so 

 that only the mandibular and maxillary segments are post- 

 oral. According to my view, however, the homology of the 

 Insectan antcnnaj with the rest of the ventral extremities is 

 placed beyond all doubt both by their post-oral position, which 

 has been conclusively proved in the case of many Insects, and 

 also by the presence of a mesodermal somite belonging to the 

 antennse. I am therefore constrained, at least until the 

 appearance of the detailed paper by CarriJ^re, to rely solely 

 upon my own observations upon the development of the 

 cephalic nervous system in Phyllodi-omia and upon Ticho- 

 niirow's statements as to the embryonic cephalic appendages 

 in Bomlyx mori (which I find to be confirmed by my own 

 observations upon Gastropacha pint). It seems to me that 

 it is sufficiently clear from these observations that, if there is 

 any homology at all between the antennee of Tracheata and 

 Crustacea, the antennee of Insects can only correspond to the 

 second pair of antennaj of Crustacea, since the antennary 

 ganglia (the embryonic antennary lobea) of Insects strictly 

 belong to the primary trunk, and, just as in Crustacea, do not 

 become fused with the rudiments of the pre-oral ganglia until 

 later. For the same reason I consider that the cheliceras of 

 Arachnids are also homologous with the Insectan antennas. 

 As to further homologies of the mouth-parts and the other 

 extremities of Arthropods, I consider it to be quite impossible 

 to give a comparative table of them at the present time, as 

 has become the usual practice. Such tables are in my opinion 

 premature, since the question of the composition of the Arthro- 

 pod head proves to be much more complicated than is gene- 

 rally supposed. The very ftict, observed by Tichomirow, 

 Biitpxhli, Carribre, and myself (in Gastropacha j^i'ni), that 

 small appendages are situated between the antennas and 

 mandibles, is sufficient to warn us to be cautious and that we 



