224 



HUBERT M. MORRIS. 



antennae are exceedingly small and inconspicuous, being situated just above the 

 bases of the mandibles. The structures which were previously considered to be the 

 antennae (6) are lateral protuberances of the labrum. 



Fig. 5. Head of fully grown larva of Bibio marct, ventral view,, x 53 ; /, labium ; 

 md, mandible ; mp, maxillary palp ; mx, maxilla. 



The body is nearly cylindrical, but somewhat flattened dorso-ventrally, and 

 normally is slightly curved, the ventral surface being concave. The body is divided 

 into twelve segments, of which the first is the longest. It bears ten pairs of spiracles, 

 which are situated a pair on each segment except the second and eleventh, and 

 project slightly from the body. The spiracles on the first segment are about twice 

 the size of those on segments 3 to 10, and those on segment 12 are about four times 

 the size of those on segments 3 to 10, and each one has two openings. 



Fig. 6. Antenna of larva of 

 Bibio marci, X 580. 



Each segment bears a number of stout conical processes, which are arranged 

 more or less in rows, on both the dorsal and ventral surfaces, the more lateral processes 

 in the rows being usually at least twice as long as the median ones. The arrange- 

 ment of these processes does not appear to vary in the different species of Bibio 

 which have so far been examined. 



