Miscellaneous. 199 



I give this remarkable Nemertean the name of Avenardia Priei, 

 dedicating it at once to M. J. Prie', a zealous naturalist of Pouliguen, 

 and to M. Avenard, Assistant to the major of Pouliguen, who fur- 

 nished me with the materials of this investigation, and facilitated 

 these sufficiently troublesome researches with a kindness for which 

 I am glad to thank him publicly. — Comptes Rendus, July 8, 1878, 

 p. 72. 



Observations and Experiments on the Mir/rations of Filaria rhyti- 

 pleurites, a Parasite of Cockroaches and Rats. By M. Osmax 

 Galeb. 



In 1824 Deslongchamps discovered, in the fatty body of the 

 common cockroach (Periplaneta orientalis), a great number of small 

 lenticular bodies visible to the naked eye, in which he found a 

 small Nematoid worm to which he gave the name of Filaria rhyti- 

 pleurites. This encysted worm merely represents the asexual state 

 of a Ncmatoid, the migrations of which have hitherto remained un- 

 known. 



The cyst forming the cell of this animal is composed of two 

 membranes : the external, which is fibrous, is easily coloured by 

 carmine ; the inner one, on the contrary, which is structureless and 

 sometimes presents a granular appearance, does not fix the colouring 

 matter. The larva, whose movements may easily be followed through 

 the wall of the cyst, is folded several times upon itself and surrounded 

 by a whitish granular matter. 



These Nematoids cannot quit their prison so long as the Peripla- 

 neta, of which they are parasites, continues alive. If by dissection 

 we separate the cysts and then place them in a suitable liquid, the 

 little worms soon pierce their cells ; half an hour of submersion gives 

 them all their liberty ; and their vitality is such that they can re- 

 main alive for three days, or even more. 



It is by chance that I have discovered the course of the migrations. 

 The baker with whom I was lodging, knowing that I was interested 

 in natural history, placed at my disposal all the rats caught in his 

 traps. On opening the stomach of one of these animals (^Mus 

 decumam(s), which I killed in order to make some histological pre- 

 parations, I found a Nematoid in the sexual state, and easily es- 

 tablished its identity with that which I had met with in the adipose 

 tissue of the cockroach : a cutaneous fold which exists in the body 

 of the larva at but a short distance from the anterior extremity 

 occurs also in the adult animal at the same part ; and it was this 

 characteristic fold that suggested the name rhytipleurites, given by 

 Deslongchamps to the encysted worm. 



The Nematoid when set free grows rapidly ; for the larva con- 

 tained in the cyst does not measure more than 11-16 miUims., 

 while the adult worm often attains a length of more than 2centims., 

 the male being, as usual, smaller than the female. 



The cuticle is thick, regularly annulated ; in the larva it contains 

 numerous porous canals. The muscular system forma a continuous 



