14 CLAVICORNIA. [A'jtithiditun 



ACATHIDXU1VI, Illigcr. 



This genus contains about fifty species which are chiefly found in 

 Europe, Northern Asia, and North America ; in all probability many 

 more will be discovered ; one or two have occurred in the Canary Islands ; 

 they are small shining, more or less globose, insects, many of which have 

 the power of rolling themselves up into a ball like Clambus ; they are 

 usually black or brownish, but occasionally the thorax is bright red ; the 

 antennae are terminated by a 3-jointed club ; the mandibles are stout, and 

 the left one sometimes strongly projects or is furnished with a process 

 varying from a small tooth to a long curved horn ; the thorax has the 

 posterior angles rounded and the margins always more or less distinctly 

 lighter ; the mesosternum is more or less plainly carinate ; the tarsi are 

 variable in the female, which sex in some species has the anterior tarsi 

 with five joints and the rest with four, and in other species has four 

 joints to all the tarsi ; the elytra are not striated on disc, and even the 

 sutural stria is often wanting or very much abbreviated. Thomson 

 divides the genus into two on the formation of the meso- and rneta- 

 sternum, but his division is not satisfactory, as it does not separate the 

 species that have variable tarsi in the females, a character that has much 

 more weight than the comparatively slight differences on which he founds 

 his two genera. The species of Agathidium are found under bark, in 

 fungi, moss, dead leaves, &c. 



The larvse of Agathidium appear in many points to strongly resemble those of 

 Leiodes and Cholera ; that of A. seminulum. according to Ferris, has the segments 

 clothed with a coriaceous skin in the place of corneous scuta ; the mandibles are bi- 

 dentate, and the eight first abdominal segments are furnished with a small tubercle on 

 each side ; the last segment is terminated by two cerci and a long clavate anal 

 appendage ; the whole surface is set with whitish silky hairs ; the larva of A. mandi- 

 bulare is described by Schiodte as oblong-ovate, convex, of a pale fuscous colour, witli 

 the corneous parts fuscous ; antennae and legs short and stout ; cerci stout, sparingly 

 setulose, scarcely as long as the ninth abdominal segment ; these larva are found in 

 the same habitat as the perfect insects. 



I. Elytra with flatly and widely rounded shoulders; 

 female with the anterior tarsi 5-jointed and the 

 intermediate and posterior tarsi 4-jointed ; insect 

 with complete ability to roll up into a ball.* 

 i. Elytra with a sutural stria reaching middle, finely 

 but distinctly punctured. 



1. Head and thorax bright red, elytra deep black, 



considerably longer than together broad . . A. NiamrENNE, Kuj. 



2. Upper surface black or deep brown, elytra 



scarcely longer than together broad. 

 A. Third joint of the antenna) very long, as long 

 as the next three together ; thorax broadest 

 behind middle ; size larger and broader . . A. ATEUM, Payk. 



* The German term for this " Kugelvermogen Vollstamlig," is very expressive, and 

 might with advantage be literally translated and adopted by Euglish'authors. 



