262 NATURAL HISTORY OF ARTHROPODS. 



tain groups, such as the Hydrobatidse, Veliidas, and Hydrometridas, are to some extent 

 aquatic, but their motions are chiefly directed upon the surface of the water, into 

 which they never plunge, except from urgent necessity, and in which they are not 

 able to survive for any considerable length of time. These are all truly aerial insects, 

 and take their food upon either the surface of the mud, the water, the land, or above 

 it in the trees. First among the former of these we find the GALGULID^E. This 

 family is composed of dark brown or blackish insects which pass their lives on the 

 muddy margins of streams, or about the outer parts of marshes, where the soil is moist 

 but not continuously submerged. They are short, clumsy-looking insects, with a 

 thicker body than any of the foregoing, with a nearly vertical, shield-like, triangular 

 face, eyes bean-shaped and prominent like those of a crab, the rostrum short, stout, 

 acute, directed horizontally backward ; a prothorax knobby and humped above the 

 level of the short, blunt wing-covers ; stout, spinous, short fore-thighs, surmounted by 

 cruel, thorny, bent shanks, terminated by a pair of long, sharp nails. The hind-legs 

 are much longer than the others, spinous, and attached to round, rotating coxas, which 

 gives them great freedom of motion. One exception to these general statements 

 occurs in the genus Pelogonus. It is not of the gloomy mud color which we have 

 cited, but is more or less tinged with bluish on a clearer dark-olive ground, marked 

 with orange on thorax and sides of abdomen, and is destitute of the asperities so con- 

 spicuous upon the upper surface of the other genera. The fore-legs are also slender 

 and fitted for running; not calculated for seizing and holding prey as in Galgulus 

 and Mononyx. The rostrum is, however, a dreadful instrument, sharp as the finest 

 needle, extremely thick and stout at base, and a deadly probe to the poor larva of 

 horse-fly or other insect which lives next the surface of the ground in situations near 

 water. 



The genus consists of but few species. One inhabits Europe, and is distributed 

 from France into Africa, and thence as far south as to the Cape of Good Hope. Thus 

 far seven species have been discovered. Of these, four came from Asia, one from 

 Central America, one from Europe, and one from the United States and West Indies. 

 The color of all these species is much the same, that is, a velvety bluish, or black 

 tinged with blue, more olivaceous beneath, with a spot of bright yellow on each lat- 

 eral margin of the prothorax, and a series of spots of the same color either on the con- 

 nexivum, or on the outer margin of the wing-covers. They all have a pair of minute 

 ocelli between the eyes ; and the antenna?, although attached beneath the eyes, are not 

 let into a hollow, but stand out free and exposed. These organs are also slender and 

 composed of long joints. 



Our native species, P. americanns, is a velvety blue, black beneath, marbled with 

 deep black above and sprinkled with golden yellow points ; the face is coal black, and 

 the rostrum piceous. Each side of the prothorax, behind the front angles, there is a 

 bright yellow spot of variable size ; the prothorax is transverse, but a little narrower 

 than the abdomen, and the lateral margins are depressed and thin, on the costal mar- 

 gin of the corium five not very distinct yellow spots appear. The legs are slender, 

 dull yellow, tinged with piceous, and the knees, tips of the shanks, and ends of the 

 tarsi are pitch brown. This is a gay, active little insect, which measures only one- 

 fourth of an inch in length, and lives among the grass and weeds on the margins of 

 brooks and ponds from Massachusetts to Texas. It is also not uncommon in the 

 island of Cuba. It differs from the very similar European species in being narrow in 

 front, and in lacking the spots on the underside of the connexivum. 



