THE ESSEX FIELD CLUB.
263
that he had found two Palaeoliths at the place marked "Wallend" on the inch
Ordnance Map, one mile west of Barking Town.
Mr. W. White exhibited various insects that had been taken on the occasion of
some of the summer excursions of the Club. One, a somewhat uncommon
insect, belonging to the Neuroptera - Planipennes, Osmylus chrysops, L.
(O. maculatus, St.), was caught near Sawbridgeworth, while on board the barge
on the river Stort, during the meeting on July 18th. Another, a local moth
(Myclois cribrum), which is restricted in its distribution chiefly to the Essex coast,
was taken in the pupal stage on the "Saltings" at Brightlingsea, May 20th
last. The larvae pupate in the stems of the thistle, and Mr. White had remarked
that most of the thistle plants in that locality were packed with the chrysalids
as closely as well could be. On the same occasion he and several other members
took some larvae of the "Essex Emerald Moth" (Phorodesma smaragdaria),
as already recorded in the Essex Naturalist (ante p. 116), and in ex-
hibiting two preserved specimens of this curious larva, Mr. White wished to
add that he had not wasted these rarities, as perhaps might be inferred from
the Editor's note in the report of the Colchester meeting ; but he had been able
to correct some slight errors that had been made in some previous descriptions of
the caterpillar. Of the eight or ten larvae captured, he had four, two of which
he had carefully preserved, while the other two died. Having exhibited these
insects at the Entomological Society in June, Mr. White read some extracts from
the published report of that meeting (Proc. Ent. Soc, 1888, pp. 20 and 21).
The larva, he said, had been described as living in a case formed from its food
plant (Artemisia maritima), whereas its habit is to only partially cover itself
with those particles of its food which it had bitten off the plant during its feeding,
and these particles were caused to adhere to the surface of the insect by means
of a sticky exudation, as noticed by Mr. George Elisha (Trans. Entom. Soc.
Lond., 1886, p. 466), but a remarkable thing about this habit is that it is
attained by a highly specialized means. Actual excretory glands had become
developed for this purpose, disposed irregularly upon various segments of the
body ; they are seen, with the aid of a strong lens, to be prominent elongate
processes of a whitish colour, each bearing at their top a single, stiff, rather long
hair, which, doubtless, serves to spike the fleshy substance of the Artemisia.
Sketches were shown in illustration of this point. Mr. White thought there
could be no doubt—although he found no result could be produced artificially by
applying gentle pressure externally to the glands—that they really possess the
functional value claimed for them, as evidenced by the fine dust particles and
larger fragments of leaf which were seen to be still firmly attached to the insects
notwithstanding the rolling to which the skin had been subjected in the pre-
serving process. There are not any particular "humps" upon certain segments,
as had been stated in some descriptions, unless the glandular protuberances just
described are intended, and this is impossible; but the skin in the sub-spiracular
region is much wrinkled, forming an irregular and somewhat flattened fringe upon
the sides of the anterior segments, adding greatly to the general protective
resemblance to its food plant, which is so strong a feature of the insect.
Mr. Oldham exhibited some Lepidoptera taken this season in Epping Forest.
Among them was Scotosia rhamnata, and a very remarkable aberration of
Argynnis euphrosyne, taken near Theydon Bois, on June 4th. In this specimen
(a 6) many of the usual black spots on the upper side of the fore-wings are
absent, and the double marginal row of black spots is indistinct, the spots