10 NOTES ON CHALCIDI*:. 



to certain general coloration laws." The fore tarsi of Chaleidiae are 

 most usually darker than the four posterior tarsi. Dr. Walsh 

 considers this as a decisive proof of a common origin and as adverse 

 to the doctrine that every species was independently created. The 

 " certain definite colorational pattern " is very conspicuous in the 

 Eurytornidae, and includes them under one head, which may be said 

 to be primarily represented by Eurytoma. The other three genera, 

 Systole, Decatoma and Isosoma, have much more affinity to Eurytoma 

 than they have to each other. The antennae of Eurytoma are stated 

 by Dr. Walsh to be 8-jointed, with the exception of E. gigantea, in 

 which they are 9-jointed. The antennas of Isosoma are said by him 

 to be 9-jointed, and those of Decatoma 7-joiutcd in the male and 

 8-joiuted in the female, omitting the two very minute joints that 

 follow the second, and considering to be only one joint. But these 

 apparent differences may be owing to the structure of the club, of 

 which the divisions are in some species contracted into one joint and 

 in others they form three distinct joints. The joints of the antennas 

 of the male in the more typical species of Eurytoma are dilated on 

 one side ; in others they are equal, like those of Isosoma and of 

 Decatoma. Isosoma has not the semicontractile and compressed 

 body of Eurytoma and Decatoma, but in some species, such as 

 E. Cestius, E. atra, and E. Philager, the body is like that of Isosoma 

 in structure. The colour of the body in Eurytoma is black, but in 

 E. bicolor, a North American species, it has the "colorational 

 pattern " which characterizes Decatoma, and in E. Philager, a South 

 American species, there are two pale humeral spots like those of the 

 European species of Isosoma. In Decatoma the ground hue of the 

 more typical species is black, but in the whole series of species this 

 hue changes by degrees to yellow ; the pale marks appear first on the 

 head and on the prothorax and thence spreads over the rest of the 

 body, which in some species is wholly yellow, and especially so in 

 D. Orctilia and in D. Diphilus, of which the first inhabits the West 

 Indies and the second South America. Others, in which the yellow 

 hue prevails, resemble some species of Megastigmus, a genus of 

 Torymidie, in the markings, and the latter have also a quadrate 

 prothorax like the Decatomae. The typical species of Decatoma, both 

 in Europe and in North America, are parasitic on the Cynipidae of 

 oak-galls, and they also agree in having a black band on the fore 

 wing. Cynips lignicola, the dweller in the well-known Devonshire 

 gall, brought with it into England two parasites, Callimome Devon- 

 iensis and a Decatoma. This Callimome has a long oviduct, which 

 can reach the centre of the gall in which the grub is cradled, but 

 such is not the case witli the Decatoma. The mode of ovipositiou of 

 these two species lias not, I believe, been yet described in England. 

 In Isosoma the "colorational pattern" is different from that of 

 Decatoma and of Eurytoma bicolor. All the species are black ; those 



