83 



Miss Hum's paper — 



Notes on the Value of Adding Acetic Acid to Alcohol 

 IN THE Preservation of lar v.« — 



was withdrawn. 



The meeting then adjourned. 



At g o'clock in the evening the section reassembled in Room A, 

 when the President called on Karl Jordan to give his paper 

 (written conjointly with Malcolm Burr) on : 



Arixenina Burr, a vSuborder of Dermaptera. 



A second species of the peculiar genus Arixcnia, discovered 

 in a cave in Java by Herr Jacobson, and named by Burr 

 Arixcnia jacohsoni. Differences between this species and .4. esaii 

 in general proportions, mouth-parts, internal organs. Habits, 

 morphology, and anatomy, particularly organs of reproduction. 

 Viviparity. Illustrated by lantern (cf. Vol. II., p. 398). 



K. Jordan then read a paper on : 



Viviparity in Polyctenid.î;. 



The family of Polyctenidcc is closely allied to the bed-bugs ; 

 the species are only found on bats. Internal anatomy not yet 

 studied, as material is very rare in collections. A specimen in 

 the British Museum contains large embryo bearing combs onlv 

 on the head, while the mother has combs on head, thorax, and 

 elytra ; less developed embryos observed in other species. Illus- 

 trated by lantern (cf. Vol. II., p. 342). 



Discîissioii. 



P. Speiser bemerkt, dass die Auftindung des Embryos mit 

 nur einem Dorsalkamm bei einer Art, wo die Nymphe zwei und 

 die Imago drei Dorsalkämme hat, eine schöne Bestätigung des 

 biogenetischen Grundgesetzes von Haeckel bedeutet. Denn die 

 Kämme sind sekundär erworbene Aupassungscharakterc, die ur- 

 sprünglich gefehlt haben müssen und erst allmählich in reicherer 

 Ausbildung auftraten. Die ontogenetische Entwickelung wieder- 

 holt hier die phylogenetische. 



