100 Rymer Jones, on Corethra plumicornis. 
object, to dwell upon the general form and appearance of this 
elegant but ferocious creature, — the symmetry of its shape, 
the vivacity of its movements, the fan-shaped plume beneath 
its armed tail, which, like a fin, propels it through the water, 
its pike-like voracity, or the ruthlessness with which it makes 
an onslaught on its prey ; and yet the descriptions of it, 
given even by modern entomologists, are lamentably meagre, 
and give but a feeble idea either of its carnivorous propensi- 
ties or its formidable armature. Its mouth presents a ter- 
rible apparatus, composed of numerous pieces, the homologies 
of which might furnish interesting subject for discussion. In 
their disposition they remind us of the foot-jaws of some of 
the Branchiopod Crustaceans (such as Chirocephalus ) , and in 
like manner are equally instruments of progression, and 
weapons for the capture of prey. The anterior pair, articu- 
lated to the apex of the snout, are of great strength, and are 
moved by powerful muscles, distinctly seen through the 
transparent covering of the head. At their extremities they 
bear fan-like tufts of stiff setse, that, when expanded, form 
powerful oars, the downward strokes of which, when ener- 
getically made, have a marked effect in aiding the progress 
of the animal through the water. More frequently, how- 
ever, their movements are of a gentler character, and only 
serve to cause the influx of a constant stream towards the 
mouth, the effect of which extends to a considerable distance, 
attracting, like a little Maelstrom, the smaller animals that 
come within its vortex. 
The second pair of these oral appendages presents a very 
different structure. They are composed of numerous narrow 
laminae, much resembling, in their arrangement, the plates 
of whalebone in a whale’s mouth, and indeed they perform 
a very similar office. These plates, represented in the draw- 
ing (PL IX) in a collapsed condition, can be spread out like 
the walls of a tent, so as to enclose as in a net whatever small 
animals may be brought within their expanse by the intrant 
current above alluded to. 
The third pair consists of two elegantly-shaped instruments 
wherewith the creature adjusts, as with a pair of hands, the 
position of the imprisoned victim, so as to pass it easily along 
the fatal road, and hand it to the embrace of 
The fourth pair, which in function at least must be com- 
pared to palpi. These pieces are of large dimensions, fur- 
nished at their extremities with sentient vibrissse, that remind 
us of the whiskers of a cat, and with a terminal tuft of greater 
strength and thickness, whereby the prey is seized and passed 
backward to the gaping jaws. 
