OHIO BIOLOGICAL .SURVEY 



on a level with the bod}' surface or very slightly elevated; the posterior 

 ones situated at the apex of two short, rigid, firmly-chitinized, cylindrical 

 breathing tubes which are always closely apposed (except in very 3'oung 

 larvae), never bifurcated except very slightly at the extreme tip; this 

 is one of the most characteristic things of this type of larva. The body 

 is flattened ventrally, making a sort of creeping-sole, elongate-ovate in out- 

 line, tapering toward the anterior end. Pro-legs are wanting or very 

 imperfectly developed as ventral folds of the body wall. 



The indications of segmentation externally are groups of irregular, 

 transverse wrinkles on which are situated, in each segment, typically 

 twelve spines, hairs or bristles in a transverse row: three pairs dorsal, 

 one pair lateral, and two pairs ventro-lateral. These I believe have never 

 before been described. For convenience of reference (and to distinguish 

 them from the minute, bristly hairs which sometimes cover the integu- 

 ment generall}' on the dorsal 



side which we may designate Yen'lroAoferal CormCL 

 integtanental bristles) I have ', lQor30-\aWa\ Carmo. 

 pleased to call the former tJic \ \ 

 segmental spines; and to name 

 them, in order, beginning with 

 the pair nearest the mid-dorsal 

 line, and proceeding laterally: 

 (a) median, (b) dorsal, (c) 

 dorso-lateral, (d) lateral, and 

 two pairs of ventro-laterals, a 

 posterior ventro-lateral , (e) and an 

 anterior ventro-lateral , {{) as one 

 is in front of the other. ( Fig. B. ) 



On the basis of the segmental spines nine segments can be clearly 

 made out posterior to the one bearing the anterior spiracles. These 

 spiracles may be considered prothoracic; hence we have ten segments 

 exclusive of the head. The head segments are retractile, somewhat 

 indefinite, with some appearance ofl:>eing two in number. For convenience 

 of reference, therefore, the total number has been considered as twelve, 

 making the prothoracic segment number three. 



The mouth-parts in this type consist of two V-shaped, jaw-like 

 pieces working verticallj^; and several pairs (commonly three or four) of 

 mouth-hooklets situated at the side of the jaws and adapted to work 

 transversely. J. B. Smith ( in discussing the larva of Syrphus torvus) refers 

 to the larger of these mouth-hooklets as the mandibles, but I doubt very 



l)i:igi-auimatiecross-seetioii of an ai)hidopliagous 

 larva. 



