HUNGERFORD: ANATOMY OF SIMULIUM VITTATUM. 375 



tends for the first Ve of the length of the vein. There a cross 

 vein connects media with radius and the vein becomes trans- 

 parent, soon branching into M^ and M,, Mj extending to the 

 tip of the wing and M. running out along the posterior side 

 of the wing. Cubitus is represented more as a fold than as a 

 vein. There are two clearly marked anal veins, anal 1 being 

 straight, and anal 2 curved; the anal area lying posteriorly 

 to the anal veins is creased by two folds. 



Legs. The legs of SimuUum are stouter than those of most 

 of the related forms. The following segments are present: 

 Coxa, a strong cylindrical segment; trochanter narrow and 

 somewhat irregular; femur, rather stout; tihia, about the 

 length of femur, also stout; tarsi, 5-jointed, joint one about 

 as long as the remaining joints taken together, the last bear- 

 ing simple claws. 



ALIMENTARY CANAL. 



The alimentary canal is a comparatively straight tube ex- 

 tending from the buccal cavity to the anal opening in the last 

 segment. (Fig. 2, PI. XLIII.) 



The Proboscis. This is made up by the close application of 

 the hypopharynx to the so-called labrum and ensheathed by 

 the fleshy labium. This strongly chitinized tube (Ph., Fig. 12, 

 PI. XLV) is well provided with muscular attachments as 

 shown by the projection drawing of a section of the head 

 (Fig. 12, PI. XLV) . At its upper end it meets the oesophagus, 

 which passes back between commissures connecting the brain 

 and suboesophagial ganglion. 



It is joined near its base with the duct of the salivary glands 

 by an apparatus shown in Fig. 11, and called by Meinert the 

 "receptaculum" or salivary receptacle (Fig. 11, PI. XLV). 



The (Esophagus. The oesophagus joins the pharynx at right 

 angles, this union being banded by a strongly chitinized collar 

 (Fig. 11, C). It is smaller than the pharyngeal box, and is 

 flanked by chitinized plates from which arise muscles that 

 correspond to Meinert's musculature of Tabanus and have a 

 similar function. 



There arises from the dorsal wall of the oesophagus, caudad 

 of the chitinized portion, a muscle that extends upward and 

 backward to take its insertion in the wall of the vertex of the 

 head. The oesophagus narrows as it passes from the head to 



S-Univ. Sci. Bull.. Vol, VIII, No. 10. 



