WERNER MARCHAND • 179 



These spiracles appear slightly projecting above the surface. 



Tahanus sp. No. 8. — An unidentified African species. No de- 

 scription but good illustration of ventral and dorsal aspect of larva 

 is given by Brumpt (1910). The larva shows dorsal prolegs well 

 developed which indicates an aquatic mode of life (Plate 4, Fig. 55, 

 a, b, c). 



Tahanus sp. No. 9. — Unidentified African species of which a poor 

 illustration is given by Griinberg (1907), (Plate 4, Fig. 58). 



Tahanus sp. No. 10. — A young specimen of an unidentified Euro- 

 pean species is figured by Graber in his work on the chordotonal 

 organs (1882-83) (Plate 8, Fig. 99); it is supposed to belong to 

 Tahanus autumnalis, and may belong to Chrysops. (See also page 

 23.) 



Tahanus sp. No. ii.— Henneguy (1904) gives the illustration of a 

 young Tahanus larva (Plate 10, Fig. 109), with typically inflated 

 tracheal trunks, in Europe. (See also pages 36 and 38.) 



Tahanus sp. No. 12. — Paoli (1907) gives an illustration of the larva 

 (Plate 10, Figs. Ill to 116) in which he studied Graber's organ. 

 Though this larva is supposed to belong either to Tahanus cordiger or 

 to Tahanus autumnalis, it is not unlikely that it is another species. 

 The two species mentioned happened to be, with Tahanus hovinus 

 and Tahanus quadrinotatus, and one or two others, the only European 

 species which had been found in the larval state up to that date, 

 but the descriptions are all insufficient. 



The larvae which were studied by Paoli live in slow flowing rivers, 

 especially in the soft mud containing decomposing organic matter, 

 among the algae, especially CharacecE, which grow in the water, in 

 places where they can easily utilize the atmospheric air as they are 

 not provided with organs adapted to locomotion in water. 



The body consists of thirteen distinct segments, of which one is the 

 head, three belong to the thorax, and nine to the abdomen; the tenth 

 segment of the abdomen is much reduced and fused with the ninth; 

 the eleventh is absent. 



