in.] METAMORPHOSES OF INSECTS. 45 



in the development of the head, and will be termed 

 the ' procephalic lobes.' I have already made use 

 of this term for the corresponding parts in the em- 

 bryos of Crustacea. The rudimentary thorax pre- 

 sents traces of a division into three segments ; and 

 the dorso-lateral margins of the cephalic blastoderm, 

 behind the procephalic lobes, have a sinuous margin. 

 It is in embryos between this and X f th of an inch in 

 length, that the rudiments of the appendages make 

 their appearance ; and by the growth of the cephalic, 

 thoracic, and abdominal blastoderm, curious changes 

 are effected in the relative position of those regions." 



In CJirysopa oculata, one of the Hemerobiidae, 

 Packard has described * and figured a stage in which 

 the body segments have made their appearance, but 

 in which he says " there are no indications of limbs. 

 The primitive band is fully formed, the protozorites 

 being distinctly marked, the transverse impressed 

 lines indicating the primitive segments being distinct, 

 and the median furrow easily discerned." Here 

 also, again, the dorsal walls are incomplete, and the 

 internal organs as yet unformed. 



In certain Dragon-flies (Calepteryx), and Hemiptera 

 (Hydrometra), the legs, according to Brandt, 2 appear 

 at a still earlier stage. 



According to the observations of Kolliker, 3 it 

 would appear that in the Coleopterous genus Donacia 

 the segments and appendages appear simultaneously. 



1 " Embryological Studies on Hexapodous Insects." Peabody Aca- 

 demy of Science. Third Memoir. 



2 Mem. de 1'Acad. Imp. des Sci. de St. Petersbourg. 1869. 



3 Observationes de Prima Insectorum Genesi, p. 14. 



