242 COLEOPTERA CHAP. 



old wood, and probably feeds on the remains of Insects therein, 

 perhaps not disdaining the cobwebs themselves. Attention has 

 been frequently called to the hairs of the larvae of these Insects, 

 but they have never been adequately discussed, and their function 

 is quite unknown. 



Fam. 44. Byrrhidae (Pill-beetles). Oval or round, convex beetles; 

 tarsi five-jointed, front coxae not exserted, transverse ; hind coxa 

 shic/di/iif the retracted femur. The ivhole of the appendages 

 capable of a complete apposition to the body. Although a small 

 family of only 200 or 300 species, Byrrhidae are so hetero- 

 geneous that no characteristic definition that will apply to 

 all the sub-families can be framed. Very little is known as to 

 their life -histories. Byrrhus pilula is one of our commonest 

 beetles, and may be found crawling on paths in early spring 

 even in towns ; it moves very slowly, and when disturbed, at 

 once contracts the limbs so completely that it looks like an 

 inanimate object. The larva is cylindrical, soft ; the prothoracic 

 and last two abdominal segments are larger than the others, 

 the last bearing two pseudopods ; its habits are unknown, and 

 110 good figure exists of it. 



The chief groups of Byrrhidae are Nosodendrides, Byrrhides 

 (including Amphicyrtides), Limnichides, and Chelonariides. The 

 first consists of species frequenting the exuding sap of trees ; 

 they have an unusually large mentuni, abruptly clubbed antennae, 

 and the head cannot be retracted and concealed. The genus 

 yosw/,'>it/i'i'ii serins to be distributed over a large part of the 

 world. The Byrrhides have the antennae gradually thicker 

 towards the tip, the mentum small, and the head and thorax so 

 formed that the former can be perfectly retracted. The species 

 are rather numerous, and are found in the northern and anti- 

 ] MX leal regions, being nearly completely absent from the tropics. 

 The Limnichides are minute Insects living in very moist places : 

 they have small delicate antennae, which are imperfectly clubbed. 

 The group is very widely distributed. 



The Chelonariides are a very peculiar form of Coleoptera : 

 oval Insects of small size with the prothorax so formed that the 

 head can be withdrawn under (rather than into) it, and then 

 abruptly inflexed, so that the face then forms part of the under 

 surface : the antennae have the basal three joints thicker than 

 the others ; these being not in the least clubbed, but having the 



