558 SECTIONAL TRANSACTIONS.— C. D. 



(6) Replacement by these solutions of altered and comminuted slate and porphyry. 



(7) Erosion, oxidation and secondary enrichment of the ore-bodies. Supergene 

 alteration of the porphyry. 



SECTION D.— ZOOLOGY. 



For reference to the publication elsewhere of communications entered in the 

 following list of transactions, see p. 685.) 



Thursday, September 6. 



Presidential Address by Prof. W. Garstang on Larval Forms : their 



Origin and Evolutional History. (See p. 77.) 



Prof. J. H. AsHWORTH, F.R.S. — The Distribution of Anopheles in Scotland, 

 with remarks on Malaria in Scotland. 



Three species of Anopheles occur in Scotland (as in England) : macuHpennis, 

 bifurcaius and plumbeus. 



MacuHpennis is recorded from four localities all in the Highlands ; it has recently 

 been taken near Kelso. Information on this species is far too scanty to support any 

 general statement as to its range ; many more areas need to be examined and careful 

 inspection made of cowsheds, pigsties, stables and outhouses. Bifurcatus is known 

 from about forty different localities ; this species is widespread both in the Lowlands 

 and in the Highlands. The localities in which A. plumbeus has been collected are in 

 proximity to the east coast or its estuaries, but it is to be remembered that, except 

 for the Clyde area, the west is practically unexamined. 



A. bifurcatus proved so troublesome by its bites in one of the districts in the county 

 of Renfrew in autumn 1926 that it became a nuisance within- the meaning of the 

 Public Health (Scotland) Act. Certain ditches, obstructed by silt and vegetation, 

 were ordered to be cleared, and this has resulted in the abolition of the breeding 

 places. 



Ague was common in the eighteenth century in Roxburghshire, Berwickshire, 

 the Carse of Gowrie and Forfarshire, and was widely distributed though less common 

 in Aberdeenshire and the neighbouring counties (Dr. J. Ritchie). Unfortunately, the 

 distribution of Anopheles in none of these areas is known, so that there is no basis 

 for a consideration of the present distribution of the species of Anopheles in relation 

 to the former distribution of ague. 



I know of only two indigenous cases of malaria in Scotland in recent years : one 

 in Forfarshire in 1919 and one (unpublished) in a south-western county in 1910. 



Mr. C. W. Parsons. — The Conus arteriosus of Fishes. 



It is difficult to delimit the pericardiac cavity in Cyclostomes ; in adult Myxinoid s 

 indeed, the posterior pericardiac wall is represented only by a rudiment. In most 

 fishes, however, the heart is confined within a pericardiac cavity having well-developed 

 walls. The hearts of a number of forms have been examined, including Raia, Acanthias, 

 Pristiurus, Lepidosteus, Polypterus, Ceratodus, Protopterus, Acipenser, Amia, Mega- 

 lops, Symbranchus, Gymnarchus, Loricaria, &c., and particular attention has been 

 paid ( 1 ) to the musculature of the structure intervening between the ventricle of the 

 heart and the headward boundary of the pericardiac cavity, i.e., the conus arteriosus ; 

 (2) to the character, number and position of the endocardiac ridges or valves that the 

 conus contains. The headward boundary of the pericardiac cavity has been regarded 

 as a fixed point and the morphological position of the valves &c. (dorsal, ventral, 

 right, left) have been worked out in relation to it. The course of evolution in two 

 directions is indicated. (1) Towards multiplication of the number of valves, conus 

 contractihty retained ; (2) towards reduction of valves, conus contractility lost. The 

 bearing of these observations on the general question of the evolution of fishes has 

 been considered. 



