THE ENTOMOLOGIST. 395 



exceedingly numerous, and one of them, Pt. latus, is repre- 

 sented in the third figure. The great abundance of some 



PTEEOMAXUS LATUS. 



species of Pteromalus also indicates its importance in 

 regulating the increase of life in other forms ; but very 

 little has yet been ascertained as to how these agencies 

 are employed, except in the well-known consumers of 

 the chrysalis, of the oak-apple grub (Teras Quercus-termi- 

 Dalis), and of the grub of the corn-fly (Chlorops). Reserving 

 more of the parasitism of this genus for another opportunity, 

 I will return to the Eurytomidaj, with which these notes 

 began. Additional observations on the species seem to lead 

 to the conclusion that the name Isosoma should be discon- 

 tinued, and that its species should be annexed to Eurytoma, 

 in which some of them were formerly comprehended. How- 

 ever, for the present I will retain the name in the descriptions 

 of new species, and will begin with one which is larger than 

 all the other species of Isosoma, and, as regards the female, 

 seems to be the European representative of the Canadian 

 I. Vitis : it has some resemblance to I. eximia and to 

 I. sociabilis, and exceeds all the three in the slenderness of 

 the antennae and in the length of the abdomen. It was found 

 near the baths of Caracalla. 



Isosoma Romana. — Foem. Nigra, longissima; caput et 

 thorax sat aspere punctata ; caput prothorace aequilatum ; 

 antennae gracillimae, fere filiformes, basi flavse; prothoracis 

 latera fulvaj petiolus brevissimus; abdomen lanceolatum, 



