hungerford: aquatic hemiptera. 151 



the resemblances would be perfect. Not only is the shape the same, the 

 "blossom end" being plainly suggested, and the exposed upper side being 

 slightly more convex than the lower, but the streakings fade out below 

 in a very similar manner. However, a closer inspection reveals a different 

 feature at each end. At the free end, just below the "blossom scar," 

 there is an obliquely-placed white crescent, whose arms extend down upon 

 the sides and mark out the cap that the young Benacus \vill later push off 

 at hatching. The browTi lines of the under surface stop short at the edge 

 of this crescent; they are still more abbreviated at the opposite end of 

 the egg. At the basal end the egg is broadly capped with uniform dark 

 brown. 



Incubation. Complete period not determined. Dr. Needham found a 

 cluster June 13. It began hatching the 23rd. 



Hatching. Dr. Needham secured a splendid photograph of the little 

 bug emerging from the shell. They came out of the egg by lifting a de- 

 tachable cap of the shell. "The embryo lies once folded within the shell, 

 its head flexed upon its breast, and its beak and legs extended flat against 

 the venter of the abdomen. Thus the dorsum of the prothorax abuts 

 against the detachable crescentic groove. The eyes appear before hatch- 

 ing as black spots upon the arms of this crescent. The back is almost 

 invariably downward, as seen in the figure, though sometimes turned a 

 little to one side. On account of the obliquity of the pale crescent and 

 the constant position of the embryo in relation to it, these eggs might 

 readily be oriented for section cutting in embryology." 



"The thin lateral margins of the abdomen unrolling at hatching, and 

 the legs becoming extended, the fledgling at once assumes proportions 

 seemingly wholly incompatible with the size of the egg from which it 

 came." 



Family NEPID^ Latr. 1802. 



Latreille, Hist. Xat. Crust. Ins., Ill, p. 252 (Xepariae). 



A. TaxojJomy of Nepid^. 



Family Characteristics. Interesting water bugs, distinguished from 

 all others by the presence of long, slender caudal filaments which are 

 not retractile. The fore legs are raptorial. The middle and hind legs 

 very little adapted for swimming. The tarsi are 1-segmented. The beak 

 is short and 3-segmented. The antennae are concealed and ocelli are 

 absent. The wings are reticulately veined. 



Three genera in America north of Mexico, Nepa, Curicta, and Ranatra. 

 Only the last genus named is credited with more than one species. It is 

 given seven by Van Duzee. 



HistoHcal Review. These strange-appearing bugs were among the 

 first aquatics to be noted in the literature. Frisch, 1727, describes and 

 figures both a Nepa and a Ranatra under the following names; 



"Von der breiten Wasser Wanze mit den zwen Fang-Klauen und der 

 hintern Lufftrohre" and "Von der grossen schmalen Wasser-Wanze mit 

 der Fang fussen und der hintern lufftrohre." This author says that 

 Johnston and Franc Rhedi had mentioned these bugs. Swammerdam 



