Tjhe Pselaphidae are supposed to feed upon Acari which they 
find amongst moss. To this family the Arcopagi belong, and 
are very nearly related to the Bythini, from which they have 
been principally distinguished by the comparative smallness of 
the 2nd joint of the antennae, as well as by their shorter max- 
illary palpi : and I find on examination, that the sexual notch 
of the anterior tibiae, first pointed out to me by Mr. Davis in 
A. puncticollis , is characteristic of the genus. 
I consider the sex with angulated basal joints to the antennae 
and notched tibiae to be the male ; but Mr. Denny gives the 
first as indicative of the female in his generic character, p. 24 ; 
yet the references to the figures in his pi. 5. are opposed to 
that opinion. 
Four British species are recorded by Mr. Denny. 
1. A. bulbifer Reich, tab. 1 .f. 6. — Den. pi. 5. f 1. 
Length |4hs of a line. Pitchy-black, shining, slightly 
pubescent; palpi ochraceous; antennae and legs dull 
castaneous ; tibiae and tarsi somewhat ochreous ; tho- 
rax obovate-globose ; elytra sparingly but strongly 
punctured. 
Found in moss in woods and on marshes towards 
the latter end of the year abundantly in Norfolk, by 
Mr. Denny and myself ; Humby and Norton, Lin- 
colnshire, from December to April, Mr. Davis; 
Newcastle, Mr. Wailes. 
2. A. clavicornis Panz. 99. 3. — Reich, t. \ .f. 7. — Den. pi. S.f 2. 
Length nearly a line. Dark chestnut. Palpi pale fer- 
ruginous: thorax rather large globose, a little nar- 
rowed behind, punctured at the base, with an im- 
pressed line: elytra thickly punctured and pilose: 
legs testaceous, tarsi yellowish, thighs clavate. 
Among moss about Crwmlyn Burrows near Swansea, 
Mr. Dillwyn; and at Falmouth, in sandy situations, 
I believe in May. 
3. A. puncticollis Den. — Curt. Brit. Rnt. pi. 422, — a beautiful 
variety of the male. 
In moss and damp situations at Horning, Norfolk, 
Mr. Denny ; abundantly in moss from Humby, in the 
winter, Mr. Davis; also at Hertford, Newcastle, and 
Netley in Shropshire. 
4. A. glabricollis Reich . t. \.f. 8. — Den. pi. 5.f. 4. 
Length f-ths of a line. Piceous black or dull castane- 
ous, shining. Palpi ochreous : antennae and legs of 
the same colour or dull castaneous ; thorax obovate- 
globose, shining, with an obscure line at the base. 
Elytra darker, slightly pubescent, coarsely and spa- 
ringly punctured. 
Not uncommon in Norfolk, near London, and Bris- 
tol in the spring, and at Humby. 
The Plant is Caucalis nodosa (Knotted Hen’s-foot). 
