The species that constitute this genus vary consderably in 
form, and even in structure ; the terminal joint of the palpi 
being elongated and cylindric in some, and obtrigonate or 
ovate-truncate in others : in D. Boleti the basal joint of the 
anterior pair of tarsi is extremely minute and concealed in the 
cavity of the tibia, whilst in the middle pair they are distinctly 
5-jointed. I have associated Diaperis with Tritoma in 44 The 
Guide,” but it is certainly a heteromerous group and cannot 
be far removed from Helops (pi. 298.), but this country is so 
poor in Heteromera that it is impossible to form any idea of 
their natural affinities from a British collection. 
I. Anterior tarsi apparently 4-jointed. 
Terminal joint of maxillary palpi elongated. 
1. D. Boleti Linn - Curtis’s Brit . Ent. pi . 358. 
Panzer having figured both the others, I have given the 
preference to this handsome species. It is found in May and 
June in Boleti growing upon trees, especially the birch, and 
was once taken in profusion at Barham, Suffolk, by the Rev. 
W. Kirby. 
II. Tarsi, excepting the hinder pair, 5-jointed. 
* Terminal joint of maxillary palpi obtrigonate. 
2. D. violacea Fab . Panz . 3. 19. — Dytiscoides Rossi Faun. 
Etrus. 
3j lines long. Ovate, slightly depressed, shining, violace- 
ous, thickly and minutely punctured. Head with a transverse 
impression at the base of the clypeus. Thorax with a shallow 
fovea at the base on each side the scutellum. Elytra with 
8 punctured striae on each. Underside pitchy; trophi, an- 
tennae and legs subcastaneous. 
Mr. Dale has taken this rare insect under the bark of trees 
in the New Forest. 
## Terminal joint of maxillary palpi oval, truncated obliquely. 
3. D. aenea Fab . Panz . 8. 2. — metallicus Fab . — ahenea Mars. 
— bicolor Fab. Panz. 94. 9. var. 
2 lines long. Pitchy eneous, ovate, shining, subdepressed, 
punctured. Elytra with 8 punctured striae on each. Antennae 
and legs transparent, castaneous. 
Taken in June and July, in sandy places at Bexley, by Mr. 
Samouelle ; under bark of trees in Kensington Gardens, 
by Mr. F. Walker; and by Mr. H. Denny, near Leeds, at 
the stump of a decayed tree; and also at Halifax in Yorkshire. 
The plant is Radiola millegrana (All-seed). 
