EMERY: SIMULIUM VITTATUM IN KANSAS. 345 



A further description by Packard is as follows: "The 

 lacina is more or less jaw-like and armed on the inner edge 

 with either flexible or stiff bristles, spines or teeth." (PI. XL, 

 fig. 15.) In S. vittatum the lacina is produced into a piercing 

 organ with an arrow-like end, with about 26 barb-like forma- 

 tions turned backward on its upper side, and it appears to 

 have a like set on the lower side. These two piercing organs 

 (the lacinte and mandibles) together with the nub-like chitin- 

 ized points on the end of the labrum, are evidently used to 

 scrape and tear away the skin in biting. The i-eason sand 

 flies or buff'alo gnats are so tenacious about holding when 

 they are sucking blood may be due to the barbed ends of the 

 lamina caught in the wound. The palpi are four-jointed, the 

 first joint being irregular in shape but about the same length 

 as the second and third joints. The fourth joint is more slen- 

 der than the second or third and is about two and one-half 

 times the length of one of them. From plate XLI, figure 28, 

 they can be seen to be sparsely covered with setae. 



"Second Maxilla," or Labium. 



Plate XLI, figure 30, shows the so-called second maxillae, 

 labium or under lip removed. It will be noticed the palpi are 

 wanting. It shows the other typical divisions of a labium, 

 the mentum, glossa, and paraglossa. The labium in S. vittatum 

 serves as a sheath for the other mouth parts. This is shown 

 in plate XLI, figure 26, and plate XL, figure 14, composite. 

 It is situated in front of the gula or gular region and is 

 bounded on each side by the gena. See Packard, A Textbook 

 of Entomology, p. 68. 



Clypeus. 



Plate XL, figure 14f, shows the clypeus of the female Simu- 

 lium. According to Packard, the clypeus "is that part of the 

 head situated in front of the epicranium, and anterior to the 

 eyes, forming the roof of the posterior part of the mouth." 

 This describes the position and location of that part of the 

 head of Simidium I have called the clypeus. Plate XLI, fig- 

 ure 29, shows a part of the clypeus of a male Simidium vit- 

 tatum. It is smaller and less developed, as are all the mouth 

 parts of the males in comparison to those of the females. 

 Plate XL, figures 20, c, 21, and plate XLI, figure 28, show the 

 torn clypeus of the female. 



