64 



[March, 



close punctnration of its head and the structure of its saw. Both these 

 indicate that it belongs to the form now under consideration, and not to 

 that described in my last paragraph. 



The basal joint of the antenna is commonly more or less marked 

 Avith yellow in both forms, but it is not invariably so in either. The 

 form with normally black scutellum generally shows (especially in 

 the d (5) broader yellow fasciae at the margins of the intermediate 

 abdominal segments (from segment 3 onwards), but this character, 

 again, is variable. 



Two questions, then, arise, viz. : 1. Which of these forms is to 

 retain the name arcuatiis ? and 2. What shall we call the other ? 



1. As Forster expressly states that the scutellum of arcnafus is 

 yellow, and nothing in his description excej)t this seems more charac- 

 teristic of one form than of the other, it would seem that we ought to 

 apply his name to that which I have first mentioned in this note — 

 viz., the species with normally yellow scutellum, propodeal band (in 

 the 5 ) normally abbreviated laterally, shining head, and saw of the $ 

 with details as in fig. 1 {infra). 



2. For the other, I propose the name perkinsi, n. sp., in honom- of 

 its real discoverer, since I cannot satisfy myself that it is identical with 

 any of the forms described by authors, either as subspecies of arcuatus 

 or as species related to it. Several of these have a black scutellum, but 

 each of tliem is separated from perTiinsi by some apparently constant 

 external character, and their saws, so far as I have examined them, are 

 all of the arcuatus type. 



The difference in the saws of the two forms is more easily explained 

 by a figure than by a detailed description. I have, therefore, photo- 

 graphed a specimen of each (mounted in balsam) at the same magnifica- 

 tion and with the same lighting and time of exposure (see figs. 1 and 2). 

 The so-called " teeth " of these saws will be seen at once to be shaped quite 

 differently, and I find these differences constant in all the specimes which 

 I have examined. 



Both species seem to be common and generally distributed, occurring 

 side by side in many very different districts, e. g., I have seen both from 

 Devonshire, Surrey, Lancashire, etc. (and probably from many other 

 counties without recognizing them as distinct species). According to 

 all tabulations known to me — Cameron's, Konow's, Enslin's, and my 

 own in Ent. Mo. Mag. July 1912 — they fall under the definition of 

 arcuatus ; but the evidence of their saws seems to me conclusive against 

 specific identity. 



