Comparative Anatomy and A ffinities of the Araucarineos. 71 



more especially those of the two last-named workers. There are no serious 

 discrepancies between the cycle in the fly sketched by Bruce, Hamerton, and 

 Bateman and that described above, except that I consider the fly history 

 to be in reality a double development. In many points my work is also in 

 agreement with that of Kleine and Taute,* except that I do not consider 

 that the " male " forms described by them play any important part in the 

 cycle. A further discrepancy consists in the view held by the latter authors 

 at the time of writing their paper in regard to the salivary gland phases 

 being a non-essential part of the cycle. My interpretation of the endogenous 

 cycle in the blood of the vertebrate is at present, so far as I am aware, 

 unconfirmed by other workers, largely, I imagine, owing to the fact that the 

 interest has been concentrated for some time past on the appearances in 

 the fly rather than on those in the vertebrate. 



On the Comparative Anatomy and Affinities of the Araucarineos. 

 By Prof. Kobert Boyd Thomson, University of Toronto. 



(Communicated by Dr. D. H. Scott, F.R.S. Received September 14, — 

 Read November 14, 1912.) 



(Abstract.) 



From a study of the anatomy of the different regions of the plant, evidence 

 is found of the relationship of the Araucarinese to the Cordaitales. 



In the first place, the presence of a leaf gap opposite the outgoing foliar 

 trace, in all forms whether the leaf be large or small, is taken as indicating the 

 Pteropsid ancestry of these forms and is considered of sufficient importance 

 to preclude the possibility of the Lycopsid connection of the Araucarineae, of 

 which view Seward has been the recent exponent. The presence of a gap in 

 the cone and in the seedling seems to put the question beyond doubt, since 

 this indicates the ancestral "presence of a leaf gap. 



One evidence of relationship to the Cordaitales is found in the retention of 

 Cordaitean pitting of the tracheids in the different regions of the plant which 

 are recognised as primitive, in the cone especially, where the pitting may be as 

 much as 5 -seriate, the pits, alternate, hexagonal and extending from end to 

 end of the tracheid as in the Pteridosperms and the primitive members of the 



* ' Arbeiten aus dem Kaiserlichen Gesundheitsamte,' vol. 31, part 2. 

 VOL. LXXXVI. — B. G 



