30 ' Bulletin No. 159- 



distal tufts of long diverging setas arise from prominences 

 near the posterior margin of the posterior body segment. 

 Behind the tufts at the posterior margin of the segment are 

 two additional setse. Respiratory appendages three- jointed, 

 tapering. Length of body 5.5 mm. 



No. 3. Orthocladius sp. — This larva resembles the two 

 preceding in a general way and was taken in some numbers 

 about rocks in Straight Creek near a dwelling occupied by 

 people affected with pellagra. Cylindrical, elongate, plainly 

 segmented. Head yellowish brown, posterior margin at 

 sides definitely black. Jaws black at tips, curved, acute, 

 three sharp denticles within apex, then a strong process from 

 which springs a very finely denticulate plate expanding to- 

 ward the base of the jaw. Mentum black at lateral margin, 

 brown medially; four lateral teeth large, acute, black, tooth 

 next within smaller, brownish; the next obliquely truncate 

 and brown; median broad, plate-like, brown. Antennae on 

 small prominences, less than one-fourth the length of the 

 head; first segment longest, bearing at its distal extremity 

 two acute appendages, one nearly as long as all the remain- 

 ing segments, the second not quite two-thirds as long; 

 second segment a little more than one third the length of 

 the first. Black specks on side of head not quite contiguous, 

 the anterior much smaller and lunate. Claws of the false 

 legs of the first body division strongly curved, many of them 

 toothed. Tufts of hairs at posterior extremity on small 

 prominences. Respiratory appendages not jointed, the 

 dorsal pair longer and club-shaped. Length 4,5 mm. The 

 broad truncate median tooth of the mentum is suggestive 

 of the genus Thalassomya, as described by authors. 



No, 4 Ablabesmyia sp..— A single dipterous larva 

 found at Cary in the Left Fork of Straight Creek is very 

 different from all the above in a number of features. The 

 body is rather short and stout, about 4.5 mm. long; the head 

 relatively large, elongate and flat, with one black speck on 

 each side, with an anterior fissure. Antennas with the long 

 first segment largely concealed by an extension of the crust. 

 Hooks of anterior prolegs retractile. Each body division 



