20 THE EARLY STAGES OF TABANID^ 



The head itself, as far as it can be exserted, is strongly chitinized 

 and usually brownish in color, while the rest of the body is generally 

 pale, whitish or grayish, but in many species marked with a regular 

 dark pattern, which in others may be absent. Following the head 

 are the three thoracic segments, of which the first is the shortest, 

 and these are followed by nine abdominal segments, the last one 

 forming the respiratory tube, and the next to the last segment bear- 

 ing ventrally the anus on a fleshy prominence. The body surface is 

 generally smooth, well chitinized, and half transparent. The fourth 

 to tenth segments are provided at their anterior margin, or not far 

 from it, with a strong circular fleshy ridge, containing circular muscles, 

 and bearing the parapodia, eight in number when all are present, or 

 fewer if, as may be the case, the dorsal ones are lacking. The ventral 

 parapodia are usually better developed and placed somewhat closer 

 together. The parapodia may be retracted and exserted, and, pro- 

 vided with many curved spines outwardly, play a part in locomotion. 

 The ridges in some species are not very prominent, are usually cov- 

 ered with a fine pubescence rendering part of the body surface opaque, 

 and are often pigmented dark, forming the patterns spoken of. The 

 spinous processes of the prolegs pass through imperceptible gradations 

 into the fine pubescence of the dull or pigmented areas. 



The larva of Goniops chrysocoma differs in appearance from the 

 other known tabanid larvas by being apparently much shorter and 

 thicker in the posterior half of the body than in the anterior where 

 the segments are much tapered and considerably longer, but as the 

 figures are based on specimens preserved in alcohol, we cannot pass a 

 definite judgment on their systematic position.^ 



Integument. — The integument in general can be divided into more 

 or less distinct dorsal, ventral, and lateral areas, which differ in their 

 finer structure, all being either longitudinally striated or more or less 

 smooth and shining. The lateral areas may be subdivided into an 

 upper, middle, and lower portion, marked off from one another and 

 slightly differing in structure. All these structural features of the 

 surface of the integument are probably vestigial traces of formerly 

 more marked characteristics, and are important in any effort to sepa- 

 rate different species of larvae. 



' See also Goniops in general, p. 56. 



