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Melinda cognata Meigen 
EXPLANATION OF PLATES XXII—XXV. 
PLATE XXII. 
Male (1) and Female (2) of Melinda cognala Meigen. x 8. 
PLATE XXIII. 
(The surface structure of the snail’s skin is schematized in Figs. 1 and 3.) 
Fig. 1. Helicella ( Heliomanes) virgata da Costa, with the anterior part of its body extracted from 
the shell and with opened mantle cavity ( m.c.) showing a big second stage larva ( L .) of 
Melinda cognata Meigen. The larva has been cleared from the distended integument of the 
kidney which partly covered its body. The dissecting needle (a) points the position of the 
pneumostome of the host towards which are directed the postabdominal spiracles of the larva. 
Fig. 2. An empty shell of a young specimen of H. virgata with two larvae of Melinda cognata; 
sp., spiracles. One of these larvae developed in this shell, the second migrated thither from 
another shell as the insects frequently do before pupation, x 8. 
Fig. 3. A young H. virgata extracted from its shell and showing by transparency in its mantle 
cavity (m.c.) an egg ( ov.) of M. cognata, and, in the kidney ( k.) a first stage larva ( L .) of this 
fly. The posterior end of the larva, bearing the spiracles, protrudes into the mantle cavity of 
the host; liv., liver. The same specimen contains also the crumpled chorion of an empty 
egg belonging to the first stage larva. 
Fig. 4. Egg of Melinda cognata (a) and the structure of its surface ( b ). a x 42, b x 240. 
Fig. 5. Puparium of M. cognata from dorsal side, showing the respiratory horns ( h .). x 8. 
Fig. 6. H. virgata, retracted in its shell and showing the posterior end with spiracles of the third 
stage larva of M. cognata, protruding from the pneumostome of the host;/., foot of the snail, 
x 6. 
PLATE XXIV. 
All the figures are of the buccopharyngeal armatures of different larvae viewed laterally. 
Letters common to these figures: an., antennae; b.scl., basal or pharyngeal sclerite; int., 
intermediate sclerite; Ibm., labium; Lbr., labrum; l.h., lateral hooks; l.e., lateral emargination; 
m.p., maxillary palps; ph., pharynx; s.d., salivary duct; s.e., supplementary emargination; t., 
triangular plate. 
Fig. 7. Head and buccopharyngeal armature of the first stage larva of M. cognata. x 240. 
Fig. 8. Buccopharyngeal armature of the first stage larva of Melinda sp. probably Melinda 
gentilis. x 240. 
Fig. 9. The same organ of the third stage larva of M. cognata. x 84. 
Fig. 10. The same organ of the second stage larva of M. cognata. x 240. 
Fig. 11. Buccopharyngeal armature of the third stage larva of Sarcophaga sp. probably S. 
crassimargo. x 42. 
Fig. 12. The same organ of the first stage larva of Pollenia rudis Fab. parasite of earthworm 
(Allolobophora chlorotica Sav.). 
Fig. 13. The same organ of the first stage larva of Onesia sp. probably Onesia vespillo. 
PLATE XXV. 
Letters common to all the figures of this plate: a.g., accessory glands; c., anterior intestinal 
coeca; d.n., dorsal central nervous system; f.c., felt chamber of spiracles; i.d., imaginal discs of 
the head; i.sp., internal spiracles of the pupa; in.g., midgut; o., external opening of perispiracular 
glands; od., oviduct; oe., oesophagous; ov., ovary; p., spiracular papillae; per., peritrems of 
spiracles; ph., pharynx; pr., proventriculus; rec., rectum; r.h., respiratory horn of the pupa; 
