30 On Plectrotarsus and ^thaloptera. 



and ratlier narrow, instead of sloping transversely across the 

 upper surface of the haustelluni, they accompany the 

 liaustelluni along its lateral margins, and are at tirst sight 

 apt to be ovei looked as part of the haustellum. 



(5) The haustellum. A long narrow organ decurved at the 

 tip. Along the whole length of the narrow dorsal surface 

 runs a double series of short, comparatively broad chitin 

 plates, arranged transversely ajid end to end (tigs. 4 & 6). 

 Between these two series is a deep median furrow running 

 longitudinally. Tiie upper surface of the haustelluni is covered 

 with minute hairs. From the underside of the tip project 

 two small tubes with small hairs on them. I assume that 

 the salivary glands open at the tips of these tubes. In Phry- 

 ganea and others the salivary glands open in the same curious 

 position, {. e. on the lower surface of the haustellum. But in 

 these the opening is single, at the end of a large sausage- 

 like £ )ld of the integumejit. 



(6) The labium. There are no labial lobes. Palpi 

 3-segmented. 



Supporting Structures of the Haustellum. 



In the more specialized groups of Trichoptera with well- 

 d -veloped haustellum the latter is supported by two semi- 

 circular chitinous sclerites which run one on each side dorso- 

 ventrally from the base of the first maxilla down to the 

 ventral surface, where they end freely and do not meet each 

 other. Along the lower surface of the haustellum, situated 

 longitudinally, there are also present usually two basal 

 haustellar sclerites, longer than broad, flat, and sometimes 

 branched. h\ Pleetrotarsiis (tig. 6) both the semicircular 

 sclerites and the basal haustellar sclerites are pi-esent, but the 

 two latter are not separate pieces, but become fused at their 

 proximal ends just before bending downwards and then for- 

 wai'ds to the labium. JMoreover, they do not lie horizontally 

 {IS supporting rafters beneath the haustellum, but are inclined 

 at a steep angle within the haustellum. 



P^eferences. 



(i) KoLENATi, P. "Genera et Species Trichopteroram." Nouveaux 

 Memoires de la Societe Imperiale des Naturalistes de Moscou, 

 tome xi. 18o9, p. 266. 



(2) Brauer. Verh. zool.-bot. Ges. Wien, vul. xxv. p. 71 (1875). 



(3) Ulmer, G. ' Genera Insectorum (WytsmanJ,' 1907, p. 156. 



(4.) Lucas, K. "Beitraie zur Kenntnissder Maud werkzeugeder Tricho- 

 ptera," Archiv fiir Naturgeschichte, 1893, p. 285. 



