1920.] 37 



3 (4) Fourth joint of hind tarsi long-, only a little .shorter than the claw-joint 



(excluding the pulvillus and claws) nigerrimus. 



4 (3) Fourth joint of hind tarsi short, only about half as long as the claw- 



joint approximatus. 



The characters of the ventral segments of the males of the other 

 species have been described by Saunders and all are easily determined. 

 I have never come across any doubtful specimens. 



In separating males of the Psammochares group (i. e. Pompiliis 

 sensu lato of Saunders' book) from the Salius group — this including all 

 his other genera, excepting the very different Ceropales — the sculpture 

 of the head, as described in that book, appears to be a sufficiently good 

 character so far as our British species are concerned. It is, however, 

 useful to note the shape of the 3rd discoidal cell in Psammochai-es and 

 its allies, the lower side of this being always strongly curved downwards 

 at its basal extremity, so that the lower basal angle always forms a deep 

 or distinct angular pocket. This pocket is more or less distinct in some 

 species of the Salius group of genera, either regularly or as an abeiTa- 

 tion ; but if a distinct pocket is wanting, one can at a glance say that the 

 insect under examination is not a " Pompilus " (s. latiss.). On the other 

 hand, the females of the two divisions can never be confused, as in Salius 

 and allied genera the 2nd ventral segment is always distinctly divided 

 into two parts by a transverse groove, whether the hind tibiae be simple, 

 as in Agenia and Pseuclagenia, or serrated, as in Caliciirgus and Salius. 



Our few species of Salius (or Priocnemis) are less difficult than 

 those of Psammochares, and on the whole more naturally placed in a 

 single genus. S. affinis, however, is very different from any other, and 

 it will certainly be removed from Salius at some future time. It differs 

 from the rest in the blunt apex of the marginal cell, the radial nervure 

 meeting the costal margin of the wing almost at right angles, instead of 

 forming an acute angle with it. 



I have not been able to examine a specimen of the rare S. pro- 

 pinquus. S. exaltatus and S. notatulus are easily confused in the- 

 female sex, but can be separated at a glance on examining the tarsal 

 claws, when the difference between them in this respect has once been 

 observed. In the latter the lower tooth is comparatively more develoi>ed 

 so that the two apjiear more nearly of a size and the emargination or 

 curved outline between them is much deeper than in the former. Mr. C. 

 H. Mortimer has previously pointed out that the fourth joint of the 

 front tarsi is shorter in notatulus, but the character of a glabrous 

 prosternum and nearl}- glabrous front coxae observed by him is not 

 exliibited by the rather numerous examples of the $ that I have 



