96 On Names applied to the British Hemiptera Heteroptera. 
aecker and Birensprung, as well as Prof. Westwood, adopt 
the older name, with 7. maura as the type. Asopus, Bur- 
meister (a collective name for genera not otherwise admitted 
by its author), having for its type the well-known Zicrona 
cerulea, is limited by Dr. Fieber to one of the three species 
forming Hahn’s genus Arma—A. lurida; by Biiensprung it 
is applied to Cimex punctatus, Linn. (Rhacognathus, Fieb), a 
British species, and by Dohrn to two extra-Kuropean forms. 
Fieber, in his generic table, uses the word ‘ Podisus,” which 
would have been unobjectionable if the genus (which is very 
slightly differentiated from Arma by the comparative length 
of the joints of the antennz) is to stand; it does not, however, 
seem likely to do so. 
As examples of the second principle, I may mention the 
following :—1. Hypnophilus, a new name for the combined 
genera Macrodema and Ischnocoris, neither of which appears to 
be satisfactorily differentiated from Pterotmetus, Amy. & Serv.; 
indeed Dr. Dohrn (erroneously, I think) includes them under 
Rhyparochromus. 2. Lopomorphus, combining Acetropis (in 
pt.) and Leptopterna, Fieb. 3. Litosoma, a collective name 
for four of Fieber’s genera. 4. Sphyracephalus (since changed, 
the name having been preoccupied) for two more genera. 
5. Idolocoris, the same. It would also be satisfactory to know 
why Mr. Scott’s Monosynamma was discarded for Neocoris, 
and Macrophysa, Westw., was rejected for the later name of 
Zygonotus. Whether Allodapus and Halticus should be changed 
because of a prior Allodape and Haltica, respectively, is a matter 
of opinion; if the objection is avalid one,then numerous changes 
in all branches of natural history are inevitable—the change of 
three at least of Messrs. Douglas and Scott’s above-mentioned 
genera among them (Hypnophilus, Litosoma, and Neocoris). 
Another most unaccountable perversity is the substitution 
by so many entomologists of Hydrometra for Gerris. The 
latter name was first used by Fabricius in 1794 (Ent. Syst.) ; 
in 1796 Latreille, in his ‘ Précis,’ separated one of the species 
(Cimex stagnorum, Linn.) under the name of Hydrometra* ; 
and this genus was afterwards more systematically treated in 
his ‘ Histoire’ (1802). But in 1803 Fabricius (Syst. Rhyng.) 
quietly appropriates this name for the greater part of the spe- 
cies which he had formerly placed under Gerrits, the latter 
being reserved for a few, mostly exotic species. He still, 
* Gerris is very clearly separated (inter alia) from Hydrometra by the 
“four posterior legs long, the anterior short” (p. 86). : 
+ One common European species (now Plearva vagabunda) was retained 
in the altered condition of Gerris, and, according to the general rule alluded 
to above, this was considered by Burmeister to represent the true Gerrts 
