428 SECTIONAL TRANSACTIONS.— D. 



separate origin of the genital artery and the orientation of the heart must 

 be regarded as characters ancestral to Octopods and Decapods alike. The 

 spacious coelom, gill structure, funnel valves, and other characters which 

 apparently relate the Vampyromorphs to living Decapods are also ancestral 

 rather than definitively Decapodan in nature. The retractile filaments 

 undoubtedly represent modified arms, but since it is the second rather than 

 the fourth arm pair which is thus modified one cannot postulate relations 

 with living Decapods. The structure of the shell with its broad pro-ostracum 

 resembles that of Liassic teuthoideans and the direct articulation of the fin 

 bases upon the shell is a primitive feature postulated by Naef but not found 

 in any adult living form. 



It is evident that the Vampyromorpha represent a distinct and ancient 

 type of dibranchiate Cephalopod. They should be treated as a group of 

 equivalent rank with Octopods and Decapods. 



Mrs. M. D. Brindley. — The succession of Hetniptera-Heteroptera in the 

 afforested areas of Breckland (3.45). 



Breckland is the name given to a well-defined area in the western parts 

 of Norfolk and Suffolk. It is characterised by tracts of sandy heath with 

 a distinctive vegetation which is conditioned primarily by the soil and the 

 relatively dry climate. During the last sixteen years, about 50,000 acres 

 of this land have been aflforested with conifers, and the planting has greatly 

 modified the flora and fauna. This communication, after a short general 

 description of the region, deals with the change as it has aflfected the insect 

 group Heteroptera in a selected area over a period of seven years, covering 

 the transition from a heath to a conifer-dwelling type of population. 



At present three elements can be distinguished in the Heteroptera fauna, 

 viz. (i) widely distributed, usually polyphagous forms, (ii) species peculiar 

 to heathlands, and (iii) forms whose host-plants are conifers. By gradual 

 infiltration, as the trees grow up, the third group becomes dominant. The 

 adjustment of the different species to the changing environment, and the 

 influence of the age and size of the plantations on distribution are discussed. 



Prof. J. Stanley Gardiner, F.R.S. — Wicken Fen (4.15). 



Exhibition illustrating the Genetics and chemistry of plant and animal 

 pigments. 



One of the characters of plants and animals most frequently used in 

 genetical investigations is colour. Until recently separation of colour types 

 has depended solely on visual comparisons, which may sometimes be mis- 

 leading and are always inadequate since they represent only a first analysis. 

 Further understanding of the developmental processes involved requires an 

 analysis of the chemical nature and physical state of the pigments responsible. 

 This has become possible in some cases. 



The exhibit was designed to illustrate various phases in the development 

 of this aspect of physiological genetics from purely descriptive genetics. 

 The analysis has gone farthest in the case of flower pigments, especially 

 the anthocyanins and anthoxan thins. With these gene action can be ex- 

 amined, for the first time, in its fundamental sense, namely as governing 

 simple chemical changes, such as oxidation, reduction, methylation or. 

 glycoside formation. In other cases, as in Drosophila, the budgerigar and 

 the clover chlorophyll deficients, we know something about which pigments 

 3j.g aflTected but nothing of the nature of the changes. 



