British Homoptera-Cicadina. 33 
4th. The infraocellar line, which runs across the fore- 
head and adjoins the ocelli on their lower side. 
This line, which is frequently biarcuate and 
sometimes interrupted in the middle, is not to 
be confounded with the uppermost of the ordinary 
series of transverse lines on the frons, from 
which it is quite distinct in character. 
These details are present in various combinations in 
different species, but the whole may generally be 
observed in a well-marked example of Athysanus sordidus, 
Zett. In several species of Athysanus, &c., there exists 
a dark form, generally of the male sex, in which all the 
dark markings proper to the species are very strongly 
developed, and which has consequently a very different 
appearance to the prevalent form. Athysanus piceus, 
Scott, is a case in point. This insect is the dark form 
of Athysanus obsoletus, Kbm., as pointed out to me by 
Dr. J. Sahlberg, and since confirmed by the examination 
of a series of intermediate examples and the dissection 
and comparison of the male genitalia. In working 
from descriptions of the female only it should be borne 
in mind that the crown in that sex is usually longer and 
more pointed than in the male, and the general colora- 
tion is paler. 
TABLE OF GENERA. 
1 (6). Hlytra not overlapping at the apex. 
2 (5). Crown not sharply angular in front, 
seldom longer than the pronotum. Spe- 
cies for the most part large and stout. 
3 (4). Elytra hyaline ae ie ss .. i, STICTOCORIS. 
4 (3). Hlytra subcoriaceous Ae a8 .. li. ATHYSANUS. 
5 (2). Crown sharply angular in front, frequently 
much longer than the pronotum. Species 
small and narrow .. dye sf .. ii. DeLrocrruauus. 
6 (1). EHlytra distinctly overlapping at the apex. 
7 (12). Inner margin of the clavus much longer 
than the membrane. 
8 (11). Sides of pronotum of moderate length, 
separated from prosternum by a distinct 
keel. 
9 (10). Crown widely rounded in front. Elytra 
with many supernumerary white trans- 
verse nerves ae a S¢ .. ly. ALLyGus. 
10 (9). Crown angularly produced in front. Super- 
numerary white transverse nerves, if 
present, very few .. : oe .. Vv. THAMNOTETTIX. 
TRANS. ENT. SOC. LOND. 1888.—PART I. (MARCH.) D 
