PARASITIC-BEETLES. 
113 
to refer to some of tlie most common instances of this change in the 
introductory part of this work, and the same is strikingly illustrated 
in the history of the present tribe, in which the same species is often 
parasitic in its larva state, whilst it feeds upon the flowers or foliage of 
plants in its perfect or imago state. 
The following is a table of the families of the Trachelides : 
A. Constriction of the neck gradual and slight; anterior coxal cavities closed behind.* 
Size medium Lagriim. 
A A. Neck distinct and abrupt; anterior coxal cavities always open behind. 
J3. Thorax with a lateral margin ; abdomen usually tapering to a long point ; hind 
legs long and flat. Size small Mordellid/E. 
Bll. Thorax rounded at the sides ; abdomen not pointed. 
C. Tarsal claws deeply cleft. Size large or medium Meloidas. 
C C. Tarsal claws entire. 
D. Thorax narrower behind than the elytra, 
h. Antennae almost always filiform and simple. Size very small. Antiiicid.®. 
E E. Antenna; usually branched in the male, serrate in the female. Size 
medium or small Pyrochroii).®. 
D 1). Thorax as wide behind as the elytra. Size small Kh i prciioui ive. 
AAA. Without visible neck — structure very abnormal. Size very small. StvlomdJe. 
Family XLII. LAQRIIDJ3. 
lliis family is comprised of a small number of medium sized beetles, 
which furnish a connecting link between the Trachelides and tire Teue- 
brionidae ; having an imperfect neck, and being rather soft and flexi- 
ble like the former, but having the anterior coxal cavities closed behind, 
like the latter. Mr. Westwood states that he has found the larva of the 
European Lagria hirta on white thorn hedges; and Lyouet mentions 
having discovered the same under dead leaves upon the ground. 
There are but five N. A. species of this family. The Lagria (Ar- 
thromacra) cvnea , Say, is an elongate brassy-black beetle, nearly half an 
inch in length, and easily recognized by the remarkably elongated ter- 
minal joint ot the antenme, which is as long as the four preceding 
joints taken together. 
Family XLIII. MORDELLIDd?. 
This family contains a considerable number of small beetles, rarely 
more, and usually less than a quarter of an inch in length, and distin- 
guished by their elliptical and arched form, the head being bent down 
* The state of the anterior coxal cavities as respects their lioing closed or open behind, is a oliarac- 
tor of considerable importance in classifying the Coleoptera, especially the Hcteromora. The coxal 
cavities are the hollows in the sternum or breast plate in which the legsare inserted. Tlieantorior cav- 
ities are sometimes wholly surrounded by the crust of the stornum, when they arc said to bo closed ; 
in other cases there is a deficiency of tlio sternum directly behind the anterior ooxie, whioh is filled by 
membrane, and the cavity is then said to bo open. 
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