258 MEMOIKS OF THE CARNEGIE MUSEUM 



Some are phytophagous or gall-makers; others live in the nests of bees and 

 wasps; others are parasitic upon gall-making Hymenoptera and Diptera; while 

 still others are genuine parasites on Coleoptera and other insects, and a few, repre- 

 senting my tribe Rileyini, destro}^ the eggs of orthopterous insects. 



The family may be separated into five tribes as follows : 



TABLE OF TEIBES. 



1. Metathorax seen from above short, not longer than the scutellum, usually distinctly shorter-, and some- 



what abruptly declivous 4 



Metathorax seen from above long, always longer than the scutellum and usually gradually sloping to 

 apex (in a single case quadrate and squarely truncate behind) 2 



2. Head not cornuted ; eyes oval or ovate, not round 3 



Head cornuted, much wider than the thorax ; eyes round Tribe I. Aximini. 



3. Marginal vein slender, longer than the stigmal or rarely shorter, but never very stout or stigmated ; 



abdomen most frequently long in both sexes, in female conic-ovate or conically pointed ; auteniise 

 dissimilar in the sexes, in females usually subclavate, in males with the joints of the funicle con- 

 stricted or excised at apex with whorls of long hairs Tribe II. Isosomini. 



4. Marginal vein short and stout, stigmated, either quadrate or semicircular 6 



Marginal vein usually slender, linear, rarely stout, but never stigmated, quadrate, or semicircular 5 



5. Antennae 10- to 12-jointed, with only one ring-joint, and dissimilar in the sexes, in females filiform or 



subclavate, in males with the funicle joints excised or petiolate at apex, with whorls of long hairs or 



with sparse long hairs Tribe III. Eurytomini. 



Antennae 13-jointed, -with two or three ring-joints, and very similar in the sexes, the funicle joints not 

 excised or pedicellate at apex, and without whorls of long hairs Tribe IV. Rileyini. 



6. Antennae at the most 11-jointed, with 1 ring-joint, the funicle 4-jointed and very similar in both sexes, 



filifoi-m or subclavate, without whorls of long hairs ; abdomen short, globose, or oval, never very 

 long or strongly compressed ; hind tibiae with rigid bristles behind Tribe V. Decatomini. 



Tribe I. Aximini. 

 Mr. Peter Cameron, in Biol. Centr. Amer. Hyra., Vol. 1, p. Ill, established for 

 Axima Walker and Hontalia Cameron, the subfamily Aximinse. The two genera, 

 however, have nothing in common, are quite distinct in structural characters and 

 belong to different families. Mr. Cameron was evidently deceived in regard to 

 their relationship by a superficial resemblance in the structure of the heads of these 

 insects. Axima is clearly a eurytomid, as I first pointed out several years ago, while 

 Hontalia is a chalcidid allied to Dirhinus, and must be placed in my tribe Dirliinini. 

 Axima is parasitic in the nests of the small carpenter bees, Ceratinidx. 



TABLE OF GENERA. 



1. Females , 2 



Males 3 



2. Marginal vein four or more times longer than the stigmal vein ; antennae 11-jointed, the funicle 6- 



jointed ; abdomen long, lanceolate, compressed Axima Walker (type A. spinifrons Walk.). 



