1 893-] ENTOMOLOGICAL NEWS. 53 



4. The abdominal appendages of the Insectan germinal streak (includ- 

 ing the cerci) are homologous with the thoracic legs. Herein it makes 

 no difference whether these appendages are attached to the middle, at the 

 side, at the front or hind margin (are meso-, pleuro-, pro-, or opisthostatic 

 in the terminology of Graber), provided only that their cavity is imme- 

 diately continuous with that of the somite to which they belong. The 

 fact that the abdominal appendages usually remain unsegmented in nowise 

 tends to show that they are not of the nature of limbs, since, for instance, 

 the mandibles also are unsegmented.* 



5. Many of the abdominal appendages of larvae and perfect Insects are 

 homologous with the thoracic legs, even when they are secondary in 

 ontogeny. 



6. The primitive function of the first pair of the abdominal appendages 

 was ambulatory, as also that of the remaining appendages. The ances- 

 tors of the Insects were therefore undoubtedly homopod, not heteropod. 



7. The many-legged Insect larvae are to be derived from the six-legged 

 just as little as are, conversely, the hexapod larvae from the polypod; both 

 forms developed independently of one another. 



8. The embryonic envelopes of the Insects probably correspond to the 

 remains of a Trochosphere." 



With regard to the origin of Insects, M. Cholodkovsky believes that ex- 

 isting knowledge "seems to decide the question still more definitely in 

 favor of the derivation of the Insects from homo- and polypod and, prob- 

 ably, Scolopeitdrella-\\ke ancestors. Even Graber .... considers it 



probable that the ancestors of Insects were myriapod-like If, 



however, we weigh the great difference between the Crustacea on the one 

 hand, and the rest of the Arthropods on the other, a close relationship 

 between Insects and Crustaceans appears simply impossible. The Nati- 

 p/ius-form of larva, an exclusively Crustacean possession, the remarkable 

 resemblance in embryonic development between Insects and Peripatus, 

 and the constitution of the respiratory and excretory organs, are facts 

 which all compel us to conclude that the Arthropods are at least diphyletic 

 in crigin. The Crustacea, indeed, are to be derived from marine Anne- 

 . lids, which in the course of their development passed through the Tro- 

 chosphere stage (which in the Crustacean development became trans- 

 formed into that of the NaupHus) , while for the ancestors of the Tracheata 

 we must look to terrestrial, or fresh-water Annelids, more of the Oligo- 

 chaete type." 



Venturesome Insects.— The notes, in late numbers of the News, by 

 Messrs. Webster, Calvert and Cross, on "venturesome insects," remind 

 me that I have made the same observations in regard to all the species of 

 the genus Grapta, that I am familiar with. When collecting, if I fail to 

 secure a specimen at first trial, I always stand still and the insect is sure 

 to aligh t onjhej^ame, or near the same spot. I remember one Grapfa 



* " Whether the segmented branchial filaments of Sisyra and Sialis belong to this cate- 

 gory IS doubtful, but can only be decided by embryological investigations." 



