PTEROMALIDAE OF N.W. EUROPE n 



Antennal scape : the length of the scape (Text-fig. 4) does not include the radicula, 

 which is sometimes hidden or hard to measure. 



Axillula : a small subtriangular area on each side of the scutellum, marked off by 

 impressed lines from both the scutellum and the adjacent axilla. Apparently 

 present in all Pteromalidae, but indistinct or absent in some members of other 

 families (e.g., Chalcididae, Eurytomidae). 



Dorsellum : the central area of the metanotum (Text-fig. 3) ; the " meta- 

 scutellum " of my previous papers, and of some other authors. 



Eye : length in general means the true length as measured in the vertical axis of 

 the head ; in descriptions of the head in dorsal view, however, " length " means 

 apparent length as measured in the longitudinal axis of the body (see Text-fig. 1). 



Face : the area below the antennal toruli, between the eyes and above the clypeus, 

 bounded laterally below the eyes by the malar sulci (= " lower face " of some 

 authors). 



Frenum : the area of the scutellum lying behind the frenal groove when present 

 (Text-fig. 3). 



Frons : the area above the antennal toruli, between the eyes and below the 

 median ocellus (= " upper face " of some authors). 



Gaster (Text-fig. 6) : length is measured in dorsal view, from the junction with 

 the petiole to the tips of the ovipositor sheaths (when the latter are far exserted, as 

 in Anogmus strobilorum, the length of the exserted portion is not included in the 

 length of the gaster). The gaster comprises abdominal segments 3-9 (numbered 

 in Text-fig. 6), but in many cases it is convenient to refer to abdominal tergites 3 

 and 9 as the " basal tergite of the gaster " and the " last tergite " respectively. 



Mandibular formula : number of teeth in left and right mandibles ; thus 3.4 

 indicates three teeth in left mandible, four in right mandible. 



Mesosternum : used in the traditional sense ; the " subpleural area " of Richards 

 (1956, fig. 38). 



Pronotal collar : length of the collar (e.g., median length) is measured in the 

 longitudinal axis of the body ; breadth of the collar is measured in the transverse 

 axis of the body. 



Propodeum : length is measured along the median longitudinal line (with the 

 latter as nearly as possible at right-angles to the line of sight). 



The structure of the pleural and ventral parts of the thorax is illustrated by 

 Richards (1956, figs. 37, 38). In the main this is followed, though in the keys I 

 have occasionally referred to the " mesopleuron " in its traditional sense (meaning 

 mesepisternum + mesepimeron). 



The text-figures have been drawn by the author, using a Watson stereoscopic 

 binocular microscope and magnifications of x 50 and x 100. Some figures pub- 

 lished in earlier papers have been partly redrawn. Measurements were made with 

 an eyepiece micrometer. 



KEY TO FAMILIES OF CHALCIDOIDEA 

 1 Petiole of gaster composed of two segments, each of which is longer than 



