EURYTOMID.E. 



I Mesothorax contracted before the scutellum ; 

 disk not bordered. 



H Mesothorax not contracted before the scutel- 

 lum ; disk strongly bordered behind. ... 



if Antennae with not more than eight joints. 



B. Tarsi 4-jointed. 



a. Ulna uninterrupted and passing into the 



costa with a gentle curve. 



* Four binder femora flat, compressed, much 



developed. 

 ** Four hinder femora not flat, 

 f Parapsides distinctly separated. 

 •j4 Parapsides not separated. ... 



b. Ulna interrupted before it joins the oosta. 



* Eadius extending to half the length of the 



wing. 

 ** Eadius not extending to half the length of 



the wing. ... ... ... ... 20. Tetrastichidas. 



C. Tarsi 3-jointed. ... ... ... 21. Trichograminidae. 



To these may be added the Tetracarnpidae, which will be noticed 

 on another occasion. 



8. Eupelmidse. 



6. Encyrtidae. 

 7. Myinidae. 



16. Elasmidae. 



17. Elachistidae. 

 18. Eulophidae. 



19. Eutedonidae. 



The genera of Eurytomidae bave been distinguished as follows : 



A. Hind tibiae with some rows of fine setae. 



B. Hind tibiae without setae. 



a. Prothorax and mesothorax thickly covered with 



large punctures. 



b. Protborax and mesothorax not roughly punctured. 

 * Metathorax perpendicularly shortened. 



** Metathorax not abruptly contracted. ... 



4. Decatoma. 



1. Eurytoma. 



2. Systole. 

 3. Isosoma. 



Some species of the family require to be especially remarked, as 

 they apparently connect the genera Eurytoma and Isosoma. 



There are several British species of Isosoma yet undescribed ; 

 variations of structure in the species already recorded are indicated 

 in the following lists. 



The differences of length and thickness in the antennae of the male 

 are indicated by the five following groups of species : — 



Group 1. — I.longicomis, breviventris, dissimilis. Group 2. — I. ver- 

 ticillata, crassicornis, angustipennis, brevis. Group 3. — I. petiolata, 

 cornuta, vacillans, minor, tenuicornis, pusilla. Group 4. — I. Nepe. 

 Group 5. — I. brevicornis. 



