438 Melinda cognata Meigen 
only mentioned that the author found Atractodes exilis in August 1901 
“swarming on Heracleum, flowers in an ordinary meadow, at Lyndhurst in the 
New Forest.' There is no record of the habits of Exolytus petiolarius which 
are only known to visit the flowers of Angelica sylvestris. And, referring to the 
whole genus Exolytus , Morley writes (p. 254) that “very little is at present 
known of the economy of this genus, though both Brischke’s record of E. 
laevigatus from Tenthredinidae and Thomson’s of E. incertus Forst. from 
Syrphid larvae point to its relation with the Tryphoninae. ’' These two Ichneu- 
monids: A. exilis Hal. and E. petiolarius Thomson were bred by me under 
the following conditions: 
Several parasitised snails of H. virgata were collected bearing the third 
stage larvae of M. cognata ; they were kept in the laboratory in a jar covered 
by muslin. The Melinda larvae soon pupated and from the pupae emerged 
several imagines of Melinda , two specimens of A. exilis Hal. and two of E. 
petiolarius. 
This shows us that the Ichneumonids oviposited in Melinda larvae when 
the latter were still in the snail. The oviposition probably takes place either 
when the larva protrudes the posterior end of its abdomen from the pneumo- 
stome of the snail, or when it lays free in the decomposed mass of its host. 
III. DESCRIPTION OF THE EARLY STAGES OF 
MELINDA COGNATA MEIG. 
(a) The egg of the parasite, extracted from the mantle cavity of its host, is 
elongated, slightly curved, and 1*1 mm. long (PL XXIII, fig. 4 a), it is white, 
has a very fine granulated surface, the markings being in the form of elongated 
hexagonal cells (fig. 4 b). 
( b) First stage larva. 
As in almost all Cyclorhaphous Diptera, the larva passes through three 
stages separated by two moults. The first stage larva when full grown is 
about 2-6 mm. long. The fat .cells being poor in reserve material, the larva is 
transparent and consequently its internal organisation is easily seen through 
the skin. The larva has a small head or pseudocephalon, three thoracic and 
eight abdominal segments (Text-fig. 1). The head, as is the case in all Cyclo¬ 
rhaphous larvae, is divided in its anterior portion by a deep median groove 
into two lateral lobes which bear each a rudimentary bell-shaped antenna and 
a slightly prominent maxillary palp, the latter composed of a number of 
sensory papillae. 
On the ventral side of the first thoracic segment and near its anterior 
border are several series of black chitinous hooks with the points directed 
backwards. The meso- and metathoracic segments bear similar series of hooks 
but on these two segments they are smaller in size and fewer in number. Each 
of the first seven abdominal segments bears on its ventral surface two series 
