MB. T. J. BOLD ON HEMIPTEKA. 365 



Sub-Div. II. HYDRODROMICA. 



Section I. HYDROMETRINA. 



Fam. HYDROMETRID^. 

 HYDROMETRA, Fab. 



119. H. najas, De G. ; Doug, and Scott, 1. c. 560. 

 Abundant on the surface of running water. Of many hun- 

 dreds taken and examined not one was found with wings. 



120. H. thoracica, Schum. ; Doug, and Scott, 1. c. 562, 

 Frequents pools of water on the moors. 



121. H. lacustris, Linn. ; Doug, and Scott, 1. c. 566. 

 In ponds and ditches. Very common. 



122. 11. odontog aster, Zett. Ins. Lap. 282, 3 ; Doug, and Scott, 



Ent. Mon. Mag., III., 25. 

 Rare. Long Benton. March. 



Fam. VELIIDJ3. 



VELIA, Lot, 



123. V. currens, Fab. ; Doug, and Scott, Brit. Hem. 571. 

 Very abundant, but always without wings. Mr. Douglas — 



Entomologist's Monthly Magazine, VI., 10 — records the appear- 

 ance of great numbers of winged individuals of this species 

 (after seeking for them in that state for several years in vain) 

 in 1868, a year not at all remarkable for its warmth ; thus prov- 

 ing that it is not heat which causes the organs of flight to be- 

 come fully developed. May it not be a provision of nature 

 whereby the distribution of the species is facilitated and insured 

 by the occasional appearance of those winged broods ? or, like 

 many other curious facts in insect life, it no doubt tends to the 

 safety and continuation of the species. 



MICROVELIA, Westw. 



124. M. pygmcea, L. Duf. ; Doug, and Scott, 1. c. 574. PI. 



XIX., fig. 3. 

 The undeveloped form in plenty on the border of ponds at 

 Heaton and Gosforth, 



