256 Miscellaneous. 
duced upon the infested organism (parasitic castration &c.) are also 
of much interest, and I hope to make them known in a future 
communication. It is marvellous to see the infested T'yphlocybe 
move, leap, and fly like healthy individuals at the precise moment 
when the Hymenopterous larva quits the sac and abandons its host 
reduced to an inanimate skin. 
Dr. Thomas, generalizing with great sagacity the old notion of 
the vegetable gall, has given the name of cecidia to every morpho- 
logical manifestation caused by the local reaction of a plant to an 
animal or vegetable parasite, whence the distinction between zooce- 
cidice and phytocecidie. It seems to me that we may employ a 
parallel nomenclature for the animal galls. I propose to call these 
productions thylacie. We already know a certain number of z0o0- 
thylacie, for example the carcinothylaciw produced by the Bopyride 
upon the Decapod Crustacea, the entomothylacie, such as the tumours 
caused by the Cuterebre upon the skin of the Mammalia, or the sac 
of Typhlocyba which we have just been considering. We also know 
some phytothylacie, the coccidial tumours of fishes, the anthrax- 
pustule (bacteriothylacia), &e. 
We must also distinguish from these external thylacie the internal 
thylacic, such as the sacs of the larva of Tachinide, the Entoniscide, 
the cysts of the Vrichine, &c. The thylacia of T'yphlocybais formed 
by a gradual dilatation of the hypodermis, which secretes an abnormal 
cuticle more strongly adorned with undulated striz than that which 
covers the actual body of the insect. 
I must warn entomologists who may wish to repeat my observa- 
tions against a cause of error which stopped me for some time. A 
good many of the T’yphlocybe of the alleys of the Luxembourg are 
infested, not by the Hymenopterous larva above-mentioned, but by 
a Dipterous larva, and as the latter, when mature, issues rapidly 
from the body of its host when this is placed in a collecting-tube, it 
gets mixed with the larve of Hymenoptera which have also escaped. 
One might then be tempted, knowing the habits of the Tachinide, 
to believe that the Dipterous larva is the producer of the gall and 
the Hymenopterous one its parasite. 
This has probably been done formerly ; but I have been able to 
ascertain that the Dipterous larva occurs in the body of the T'yphlo- 
cyba itself, with the head directed towards the extremity of the 
abdomen of its host, which it distends so much as to make it 
slightly pass beyond the wings, which is not the case in the normal 
state. This Dipterous larva, after issuing through the dorsal part 
of the middle abdominal somites, becomes converted into a naked 
pupa at the surface of the ground, and I hope shortly to be able to 
describe the perfect insect.—Comptes Ltendus, July 8, 1889, p. 79. 
