Heterocerus is undoubtedly allied to Parnus ; nevertheless 
the organs of manducation present some very different cha- 
racters, especially in the absence of a joint in the maxillary 
palpus : and the 4-jointed tarsi and spined tibiae are somewhat 
anomalous to the neighbouring genera; although it must not 
be forgotten that in the Hydrophilidae the basal joint is often 
very minute ; and in our genus, to supply the deficiency, it is 
as long as the two following, as if the first and second had 
been united to form a longer base : and the same provision 
obtains in the heteromerous beetles, where sometimes the 
basal joint of the posterior tarsi is very long, as may be seen 
by referring to plate 155. 
Three species of the genus Heterocerus appear to be na- 
tives of Great Britain. 
1. H. marginatus Bose ., Fab.—Panz. 23. 12. — fenestratus 
Thunb. 
30th June, 1827, I found it in profusion on the sands at 
Broughton, Lancashire ; they were principally met with under 
small dead crabs left by the tide, beneath which they were 
burrowing into the sand. 
2. H. lsevigatus Fab. — Panz. 23, 13. 
In the spring I have met with it on marshes in Norfolk, 
burrowing into the mud on the sides of ditches and ponds. 
3. H. obsoletus.— Curt. Brit. Ent. jpl. 224. 
This species is met with, I believe, near Rochester. I have 
found it on salt marshes in Suffolk the beginning of May, at 
the sides of ditches,, running on the mud when the sun shone. 
It is the largest and darkest of the species, and much more 
densely clothed with short and dusky hair. I have not been 
able to discover any sexual character ; some specimens, how- 
ever, like that figured, have the thorax narrower than the 
elytra, whilst in others it is quite as broad and more convex ; 
these are also larger, and may be the females. 
The plant is Caltha 'palustris (Marsh Marigold). 
