364 SECTIONAL TRANSACTIONS.— D. 



14. Mr. R. C. Fisher. — Recent work in France on Parasitic Control of 



Insects. 



A visit during 1925 to entomological laboratories in France afforded an excellent 

 opportunity of observing in one country two aspects of the work involved in the 

 use of parasites for the control of exotic insects. 



1. Study and Collection of Parasites in Country of Origin of Host Insect. 

 At Hyeres, the U.S. Bureau of Entomology has established a parasite laboratory 

 for collection and study in Europe of the parasites of the European Corn-borer, 

 Pyrausta nubilalis Hb., injurious to maize crops in the United States. A study of 

 the parasites of this insect has been made in selected localities representative of 

 varying climatic and other conditions in France and Central Europe. Consignments 

 of parasites have been shipped to the United States for rearing and liberation in the 

 field. A collection was made at Bergamo, Italy, in August 1925. 



2. Colonisation and Distribution of Introduced Parasites. 



At Mentone, the French Ministry of Agriculture has established an insectarium 

 for the rearing and distribution of imported insect enemies of scale insects, e.g. Icerya 

 jmrchasi in particular, Dactylopius, Pulvinaria and Pseudococcus spp. 



Acclimatisation of Aphelinus mali for the control of the apple woolly aphis — 

 Eriosoma lanigera — is being continued in different parts of France with varying 

 results. 



The present trend of research on parasites in France is to study the entire parasitic 

 complex of one particular host-insect. Work on these Unes has been carried out for 

 Pieris brassicce at Lyons. The parasites of other injurious insects might very 

 profitably be studied in a similar way. The relations and mterrelations of host and 

 parasite, of parasite and parasite, in localities differing in climatic and ecological 

 conditions, would yield a true indication of the role played by parasites in the control 

 of any insect in its natural habitat. Such should, theoretically, be known before 

 parasites are introduced from one country into another. 



Department II.* 



* Section divided. 



1 5. Prof. F. H. Edgeworth. — The Morphology of the Eye Muscles in Lower 

 Vertebrates [demonstration of models showing development of the 

 Skull in Acipenser and in the Ganoids). 



In Dipnoi, Urodela, and Anura all the external ocular muscles are developed 

 from the walls of the first head cavitj' or homologous primordium. This is probably 

 their primary origin. 



In certain Teleostomi the recti superior, internus and inferior, and the obliquus 

 inferior are developed from the walls of the first head cavity. The obliquus superior 

 and rectus externus are developed from the distal and proximal portions of a projection 

 from the upper end of the mandibular muscle-plate. In Plagiostomi the recti superior, 

 internus and inferior, and the obliquus superior are developed from the walls of the 

 first head cavity. The obliquus superior and muscle E are developed from the distal 

 and proximal portions of a projection from the upper end of the mandibular muscle- 

 plate. Muscle E fuses with an anterior projection from the upper end of the hyoid 

 muscle-plate to form the rectus externus. 



The conditions in Teleostomi and Plagiostomi may be considered secondary and 

 tertiary modifications of those in Dipnoi, Urodela and Anura. 



These conclusions are in harmony with observations already published showing 

 that the masticatory muscles of Dipnoi and Amphibia are more primitive than those 

 of Teleostomi and Plagiostomi. 



Muscle E of Plagiostomi is probably either homologous or homoplastic with the 

 lectus externus of Teleostomi — according to the presumed ancestry of the latter group. 



The absence of any (subsequently atrophying) primordia separating from the 

 upper ends of the mandibular hyoid muscle-plates in Dipnoi, Urodela and Anura, and 

 of any such primordium from the hyoid muscle-plate in Teleostomi, casts doubts on 

 V. Wighe's theory that the primordia of the obliquus superior and rectus externus 

 of Plagiostomi represent prseotic myotomes. 



