26 



the middle and posterior pairs, and the proximal extremities of 

 the tibiae, being largely buff. 



Simulium latipes has not yet reached the Museum from any other 

 African locality, and the occurrence of this European species in 

 South Africa is very remarkable. Unless the fly has been introduced, 

 owing to larvae or pupae having been carried in the water-barrels or 

 tanks of a ship, which is possible although perhaps not very probable, 

 it would seem that the presence of 8. latipes in Natal must be 

 regarded as an instance of discontinuous distribution. 



Simulium damnosum, Theobald. 



Reports of the Sleeping Sickness Commission, No. III., p. 40 (London : 

 Harrison & Sons, 1903.) 



PLATE I., FIG. 6. 



There can be little doubt that M. E. Roubaud is correct in 

 believing that this species, which was described originally from 

 Uganda, is distributed throughout Equatorial Africa.* In addition 

 to the type and a large number of other specimens from Uganda, 

 the Museum has received examples of Simulium damnosum from 



* Cf. E. Roubaud, Bulletin du Museum d'Histoire Naturdle, T. XII., p. 141 (Paris, 

 1906). According to Roubaud (" Branchies rectales chez les larves de Simulium 

 damnosum Theob. Adaptation d'une larve de Simulie a la vie dans les ruisseaux 

 de 1'Afrique 6quatoriale " : Comptes Rendus Hebdomadaires des Seances de I' Academic 

 des Sciences, T. CXLIV., pp. 716-717 (April 2nd, 1907) ), the wide range of 

 S. damnosum and its occurrence in the hottest parts of equatorial Africa are due to 

 the complex character of the retractile tracheal gills of the larva, which, as in other 

 species of Simulium, are protruded from a transverse slit on the dorsal surface of 

 the anal segment. Roubaud regards the tracheal gills of the larva of S. damnosum 

 as an instance of adaptation to aquatic life in tropical climates, and asserts that, in 

 the case of the majority of the species of Simulium found in cold or temperate 

 regions, the larval tracheal gills are of a far simpler typo, so much so that a definite 

 physiological value as a respiratory apparatus can scarcely be attributed to them. 

 It should, however, be pointed out that, according to Johannsen, in the larvae of 

 North American species of Simulium " the retractile, translucent, respiratory 

 filaments (blood gills)," though " sometimes simple," are " often much lobed," as, for 

 instance, in the case of Simulium venustum, Say, a species widely distributed in 

 Canada and the United States, and regarded by Roubaud himself as synonymous 

 with the common European Simulium reptans, L. (Cf. O. A. Johannsen, " Aquatic 

 Nematocerous Diptera " : New York State Museum Bulletin 68, Part 6, pp. 348-349, 

 and Plate 37, fig. 9 ( 1903) ). For an account of the tracheal or rectal gills of the larva 

 of S. damnosum, the reader is referred to Roubaud's paper. 



