Morphology and Phylogeny of Insects. 445 



of somewhat modified legs. Packard's investigations*, how- 

 ever, appear not to confirm the homology of these appendages 

 with the legs, since they are said to develop from three pairs 

 of tubercles which all belong to the ninth segment. Kraepelin 

 likewise rejects the homology of the copulatory organs of the 

 drone [Apis mellifica) with the parts of the sting of the 

 female. This question needs further investigation. Matters 

 are somewhat better with regard to the male forcipes of the 

 Lepidoptera. As is well known t these forcipes develop from 

 the hindmost pair of pro-legs of the caterpillar (the so-called 

 claspers) ; but according to Tichomirow tlie latter arise from 

 the hindermost pair of the embryonic abdominal appendages, 

 i. e. from the appendages of the eleventh segment, and there- 

 fore correspond to the cerci of other Insects. For Tichomirow 

 states that the caudal lobes diminish more and more in the 

 course of the development, and finally are almost entirely 

 absorbed in the formation of the hindermost pair of the abdo- 

 minal legs of the larva, whose ninth abdominal segment 

 arises through the fusion of the sixteenth to the eighteenth 

 embryonic segments. I have shown above that in all proba- 

 bility the cerci are homologous with the true legs ; the forcipes 

 of the male Lepidoptera are consequently likewise to be 

 regarded as homologues of the legs. In the adult state they 

 are attached to the ventral half of the ninth abdominal rin":, 

 which in many species is greatly modified, but in some 

 preserves its typical annular shape. 



The gonapophyses are thus, in certain cases at least, to be 

 considered as homologues of the legs. 



In considering the morphology of the germinal streak of 

 Insects I cannot refrain from touching upon the question of 

 the relation of the germinal streak and the embryonic enve- 

 lopes to the Trochosphere-theory. We know that in 1878 

 B. Hatschek produced a scheme of the formation of the 

 Annelidan body, according to which the foremost or cephalic 

 segment is contrasted with the whole of the remaining body- 

 segments, as forming the trunk. This scheme has recently 

 also been applied to the germinal streak of Insects, which, 

 according to Haase, is composed, (1) of the antennaj-bearing 



Arten der Gattimg Botubus," Jenaische Zeitscbrift, 12 Bd., 1878, pp. 303- 

 430, with two pLates. 



* Packard, " Observations on the Development and Position of the 

 Il3'menoptera," Ann. & Mag. Nat. Hist, xviii., 18G(3, pp. 82-99. 



t Barthelemy, ' Recbercbes d'anatomie et pbysiologie geu^rales sur 

 la classe des Lt'pidopteres ' (Toulouse, 1804), 11 planches ; Kiinckel, 

 " Siguitication morpbologique des appendices servant a la suspension des 

 chrysalides," Comptes Keudus Acad. Paris, t. xci., 1880, pp. 395-397. 



