144 THE EARLY STAGES OF TABANTD^ 



the staining methods employed have undoubtedly been insufficient; 

 second, the different types of insect may show important differences 

 in the integument. If the integument is not very thick, it may 

 often be of simpler structure. But only exact observations can de- 

 termine this point. In the meantime, Lecaillon points out that the 

 structure of the integument of this larva suggests strongly that de- 

 scribed by Dubosq in the myriapods. 



Lecaillon describes also the attachment of the muscles on the chit- 

 inous membrane of the larva of this species. The muscular fibers in- 

 serted in the integument do not end at the epithelium but cross the 

 chitinous layer, becoming attached at the median zone. But the stri- 

 atlon of their fibers disappeared where they reach the integument, 

 and the whole section contained between the hypothelium and the 

 median chitinous zone is formed by non-striated fibrils forming a 

 sort of a tendon. All the muscles attached to the integument present 

 this type of insertion. Lecaillon points out that the middle and 

 external layers form the really hard and resistant part of the chitin- 

 ous membrane of the integument, as Dubosq has shown in the myria- 

 pods. This aids in the understanding of the mode of insertion of the 

 muscle fibers in the highly contractile larvae of tabanids, in this 

 region of greatest resistance. About Graber's organ, in this species, 

 see page 35 and Plate 10, Figs. Ill to 116. 



According to Bezzi, the Tabanus larva in which Paoli studied 

 Graber's organ, may have belonged to this species (Paoli). See 

 p. 37 (Special anatomy of tabanid larvae). 



Tabanus semisordidus Walker. — The egg masses of this South Ameri- 

 can species have been observed in British Guiana, by Bodkin and 

 Cleare, in 1916, to be deposited on the leaves of aquatic grasses and 

 in some instances on the leaves of young rice plants. They are laid 

 in a little bundle consisting of twenty or more cigar-shaped, shining 

 black eggs adhering to one another and to the leaf surface. 



Tabanus solstitialis Schiner. — A common European species. 

 Brauer (1880) states that the pupa is found in the water, being green 

 in color and provided with large ear-shaped anterior spiracles. The 

 larvae are not mentioned. 



