246 MR. R. SHELFORD ON MIMETIC INSECTS AND [ Nov. 4 
figs. 4,5, 6). The Brenthids are extremely variable in both sexes, 
in the matter of size, in the shape and length of the terminal 
processes of the elytra, and in the amount. of scaling on the 
head and antenne. The three species here noted range in 
length from *75 in. to 1:5 in.; and it is of exceptional interest 
that three mimetic Longicorns of sizes corresponding closely to 
these forms should be found in a more or less closely circum- 
seribed area, and all belonging to the same subfamily. 
In the first couple Diwrus syle anus (Senna) (a female) measures 
1:5 in. in length, and the mimic /goprepis insignis (Pasc.) is of 
corresponding length (compare figs. 4 & 7 on Plate XX.). Both 
species are dark brown, relieved with pale ochreous streaks and 
spots; the Brenthid has the prothorax and elytra densely and 
deeply punctured, the punctures on the elytra being arranged in 
close-set rows. Both on the prothorax and elytra each puncture 
is occupied by a peculiar scale, lenticular in shape and pale 
ochreous in colour; these produce the pale ochreous streaks 
characteristic of the beetle (fig. 4a). The head and antenne 
are covered by similar scales, more closely set and not imbedded 
in punctures; each elytron terminates in a somewhat sharp 
point, the homologues ‘of the long, narrow, terminal processes of 
the male. 
The mimic has the ground-colour of the prothorax and elytra 
black, and thei dor sal surfaces ar e covered with tufts of a fine 
pale ochreous pubescence (fig. 7a); these represent very well the 
seales of the Brenthid, and a very similar mottled appearance is 
thus produced in both species by totally different means. The 
elytra of the Longicorn do not terminate in sharp points correspond- 
ing to the points of the Brenthid’s elytra, as in the two species 
mentioned below. The rostrum of the model is shghtly longer 
thanin Baryrhynchus dehiscens, but the antenne are shorter and 
thicker; and similarly we find that the antenne of the mimic, 
which, when carried in the natural attitude (7%. e., pointing 
forward and closely apposed), simulate the rostrum and antennie 
of the Brenthid, are plumose for a greater part of their length 
than in Alibora sp., whilst the free portion is short and thick, 
not Jong and setaceous as in the Alibera. Both model and mimic 
were taken on a fallen log close together. 
Eetatosia moorei (Pasc.) is a mimic of D. shelfordi (Senna) (¢ ), 
a species of medium size, 1 inch in length (compare fig. 10 with 6 
and 10a with 4a on Plate XX.). The simulation is as perfectly 
earried out and by the same means as in -2goprepis insignis, 
with this addition, that the elytra terminate in sharp points 
corresponding to the same points in the Brenthid. The length 
of the mimic from elytra tips to termination of the plumosity of 
the antenne is approximately the same as the length of the model 
from elytra tips to tip of the rostrum. : 
Another and a smaller species, Dymascus porosus (Pasc.) 
(Plate XX. fig. 9), mimics—again by the same means—a small 
Jriurus forcipatus (Westw.) measuring only ‘75 inch in total length 
[18] 
