Acroceridae. 161 



be beaten down as beetles without flying away; it is said also some- 

 times to hower in the air. 



Geographical distribution: — Northern and middle Europe from 

 the middle ot Sweden down into France. 



2. Oncodes Latr. 



(Ogcodes.) 



Head small. Only two ocelli present. Antennæ inserted far 

 down, below the eye-suture, on the under side of the head; they 

 are short, two-jointed, the first joint thick, the second ovate with an 

 apical arista. The proboscis is rudimentary or quite absent. Erichsen, 

 (Entomogr. I, 138) stated in 1840 that the proboscis is absent, and 

 the oral aperture closed by a membrane, but in 1846 (Wiegmann's 

 Arch. I, 288), he means to have seen a short proboscis in a living 

 specimen, but it is not described more particularly. As far as I could 

 observe with a lens the facts are as described by Becher (Denkschr. 

 d. Kais. Akad. d. Wisssensch. Wien, math. nat. iClasse, XLV, 1882. 144, 

 Taf. III, Fig. 1). The oral aperture is seen covered by a membrane 

 in which is a chitinous ring, somewhat widened in front and behind. 

 Becher thinks that this formation answers to his „Schlundgeriist", 

 that is to say the pharynx perhaps together with clypeus. The 

 thorax is large and buibous; the prothoracic spiracles are large and 

 distinct, lying at the humerus. Abdomen is somewhat inflated, espe- 

 cially in the female, consisting of six observable segments. The vena- 

 tion of the wings is incomplete; in gibhosus there is a vein below 

 the costa, probably the mediastinal vein; the foUowing thick vein I 

 take to be the united subcosta and radius; from the middle of this 

 comes an unbranched vein, the cubital vein; the other veins are very 

 weak, the first of them is concave, and may be the discai vein, then 

 follows a convex, certainly the postical vein; the apical part of the 

 discai vein is convex, and it is connected with the postical vein by 

 a very indistinct cross-vein, I think the whole represents the anterior 

 branch of the postical vein; below the postical vein there is a weak 

 anal vein and a short axillary vein; there is no discai cell, but from 

 the base of the cubital vein a cross-vein stretches downwards, and 

 there are some faint end branches, showing a tendency to form a 

 discai cell. 



The larvæ are parasitic on Arachnids. O. pallipes Latr. has 

 been bred from Clubione putris, in the abdomen of which it lives 

 (Menge, Schrift. Danzig. Naturf. Gesellsch, n. Folg. I, 1866, 37), and 

 O.fmnatus Erich, from an undetermined Arachnid (see Brauer: Verh. 



11 



