560 MODERN CLASSIFICATION OF INSECTS. 
places that they reside, and as it is generally at a considerable depth 
from the surface, the hind part of the body is furnished with a very 
long and slender tube, which serves as an organ of respiration ; hence 
they have obtained the name of rat-tailed larva; the mouth is sur- 
rounded by a cartilaginous margin, enclosing a conical fleshy organ ; 
the under side of the body is furnished with seven pairs of mem- 
branous feet, provided with small hooks, being the only instance 
of such appendages which occurs in the order. When full grown 
they quit the water and bury themselves in the earth; their body 
shortens, hardens, and becomes the puparium, in which their organs of 
respiration consist of four small horns placed in the front part of the 
body (fig. 131. 8, 9. represents the pupa extracted from the pupa- 
rium). Réaumur (Mem. tom. iv. pl. 30—32) has illustrated the 
transformations of several species of these rat-tailed larvee, as has also 
Swammerdam (Book of Nature, pl. 38. fig. 9. N. B.). 
In the works of Latreille we find various methods of distribution of 
these insects into sectional and subsectional groups, differing according 
to the organs selected to characterise the division, as, for instance, 
the length of the antennz and of the proboscis, the prolongation of 
the nasus, &c. 
The family Conopsip®, formed of the genus Conops of Linnzus 
(fig. 131. 10. Conops flavipes), is particularly distinguished by having 
the proboscis long, and always exserted, elbowed, and siphon-shaped, 
either cylindric, conic, or setaceous (fig. 131. 12. rostrum of Conops) ; 
the mandibles and maxillary lancets are obsolete, those representing 
the upper lip and tongue only remaining; the palpi are minute and 
inarticulate ; the reticulation of the wings is nearly similar to that of 
the typical Muscide ; the antennz have the seta very short, and 
either terminal (jig. 131.11. ant. of Conops) or dorsal (as in Myopa); 
the abdomen is generally incurved at the extremity, with the male 
organs of generation exposed. These insects are generally prettily 
coloured, and are met with upon plants and flowers. The species are 
parasites in the larva state upon bees, as first discovered by Baum- 
hauer. Latreille also states that the Conops rufipes undergoes its 
transformations in the interior of the abdomen of living humble bees, 
escaping at the margin of the segments, having reared four specimens 
