On the Habits o/Evanla Desjardinsii, Blanch. 478 



consider the four pairs of branchiae as issuing from three 

 segments only. In certain individuals one recognizes dis- 

 tinctly, even from the outside, this insertion on four segments : 

 the first is on the fourth segment, the second on the fifth, 

 the third on the sixth, and the fourth also on the sixth, but 

 abutting a little on the seventh. In Melinna, on the contrary, 

 the four branchiae of each side arise from a common mass 

 inserted on the fourth segment ; but nevertheless each 

 branchia has its efferent vessel corresponding to a distinct 

 segment. A glance at the beautiful figures of Meyer * will 

 sufiice to carry conviction on this point. 



By combining my observations with those of Meyer and of 

 Wiren I have compiled the table given on p. 472, wliich 

 shows the homology of the anterior segments of the Ampha- 

 retida^. 



LXXIIL — On the Habits o/Evania Desjardinsii, Blanch. 

 By M. EdMOND BORDAGEf. 



Some months ago I collected in the Island of Reunion a 

 certain number of ootheca of Blatta, in the hope of seeinf>' 

 the parasites of the family of Chalcidiaj emerge from them. 

 A few days afterwards I was greatly surprised to notice in 

 the glazed box which contained the oothecae a hymenopterous 

 insect, measuring 7-8 millim., of a black colour, and havino- 

 no relation whatever with the family of the Chalcidia3. 



At the first glance the insect seemed to have the abdomen 

 atrophied or mutilated. I recognized later, after an exami- 

 nation of its principal characters, that I had to deal with an 

 Evania — abdomen short, pediculated, laterally compressed, 

 inserted into the back of the raetarhorax; antennee filiform and 

 as long as the body ; lastly, the neuration of the wings was 

 entirely that of the genus Evania. The resemblance to a 

 species found in France — E. appendigaster — caused me at 

 first to believe that it was a representative of this species; 

 but on examining more closely the rudimentary abdomen, I 

 found it to be compressed laterally, but a little more rounded 

 than that of E. appendigaster ^ which is distinctly triano-ular. 

 A search in books taught me at length that the species 

 which interested me was E. De^^jardinsii, described by 

 M. Emile Blanchard (Hist. nat. des Insectes, t. i. p. 299). 

 This species, found in the He de France, had not yet been 

 found in Bourbon, and the Natural- History Museum of 

 iSaint- Denis did not possess a specimen. 



* Meyer, ' Studien iiber der Korperbau der Anuelideu,' 18S6-1887 

 fig. 3, pi. xxii., and fig. 3, pi. xxiii. 



t From the ' Comptes Reudus,' t. exxiii. pp. 010-613 (1896). 



