312 Jlli'scellaneoiis. 



the most extraordinary energy in order to escape from their 

 prison. 



It is necessary first to make the observation that the caterpillars 

 of Sihine honaereusis, like those of other Limacodidie, as the study 

 of their cocoons has taught, provide no operculum to facilitate the 

 emergence of the imago ; these cocoons are shells, of which the 

 parchment-like tissue is homogeneous. It follows therefore that 

 these insects, whether host or parasite, must have some special 

 means of making an outlet. To this end both chrysalis and nymph 

 are armed on the frontal region with a strongly chitinized conical 

 j)oint, absolutely similar in the two cases. Both carry points at 

 the extremity of the abdomen. Host and parasite, thus armed, 

 bend themselves like a bow, then give to their bodies rapid and 

 violent gyratory movements, at the same time pressing the frontal 

 point against the anterior end of the cocoon, and in this way they 

 cut out a hemispherical cap with sharply defined borders of a size 

 proportional to their own. We have here a phenomenon of con- 

 vergence which the author thinks should be designated liomeojjraxis 

 (o/.(0(os = like, 7rpc^ts = action). 



Observation teaches what is the physiological mechanism which 

 allows the prisoners to exert a maximum of energy and to convert 

 themselves into a living brace and bit. The nymph of St/strojms 

 and the adult insect itself emerging from the nymph have a 

 volume such that they present the appearance of Anthrax and 

 Bomhylus. It is only after emergence that the adult Si/stroptis 

 takes on its slender form and shows itself under the deceitful guise 

 of a Conops. In short, the nymph possesses the faculty of filling 

 its digestive tube with air, which enables it, under the action of 

 the muscles, to compress the blood-mass which fills its general 

 cavity. It has at disposal then an air-pump, like many other 

 insects, which, as the author has already shown in the Orthopterous 

 Acridefe (' Comptes Eendus,' t. ex. 1890, p. 807, and t. xix. 1894, 

 p. 244), plays so important a role after emergence, metamorphosis, 

 and oviposition ; the augmentation of volume which the insects 

 present at the moment of emergence depends ou the dilatation of 

 the digestive tube with air, and not on the dilatation of the tubular 

 or ampxxUiform tracheae*. — Comptes liendus, tome cxxxviii. no. 25, 

 pp. 1623-1625 (20th June, 1904). 



* The Systropns parasite of Sibine bonaerensis, Berg, a special species 

 Avhich ought to bear the name of Systropns conopo'ide.t, Kiinckel, ditJers 

 from 'S'. fcenoules, "Westwood, from Mexico, by detiuite characters: — 

 1. The two lateral spots on the uietathoracic scutum are joined in one 

 and of a straw-yellow ; 2. The abdomen has the swelling at the extre- 

 mity entirely black and the sides of the constricted portion marked by 

 elongated black spots, forming a discontinuous lateral band ; 3. The 

 second tarsal articulation, both anterior and intermediate, is entirely 

 black. 



