ATLANTIC FORMS OF SYMPETRUM STRIOLATUM, CHARP. 



3 



his sanction to state that our Scottish insect will fall in his 

 revision of S. striolatum under the subspecies nigrifemur. 



Just after sending the material to Dr. Ris, Mr. G. G. Black- 

 wood, of Edinburgh, brought to me most opportunely a very 

 nice little series (four males, one female) of S. striolatum, in very 

 mature condition, which he had taken at Mallaig, Inverness- 

 shire, on September 4th last ; and having found it useful to 

 tabulate the principal characters of these and of the more typical 

 English form, I give here a reproduction of this tabulation in 

 part, along with two diagrams showing the lateral thoracic 

 markings, taken respectively from males from Thorney, Cam- 

 bridgeshire (Fig. 1) and Mallaig (Fig. 2). 



English. (Male.) 

 Line at base of the frons ends at the 



eye, without going downwards. 

 Humeral and second lateral sutures 

 very narrowly marked with black. 

 The first lateral suture in its upper 

 part hardly marked at all (some- 

 times, however, the narrow median 

 field (f, g) may be lightly outlined 

 in fuscous). 



Usually five fairly well-defined yel- 

 lowish spots surrounded by black 

 on the sides of the thorax above 

 the legs. These spots are distri- 

 buted thus on 



■ mesinfraepisternum. 



c : mesepimeron. 



^ [metinfrsepi sternum. 



[This field is the metepisternum, 

 ^j and in the typical forms is 



\ not divided into spots. 

 The above spots may be more or less 

 confluent ; thus a, b may be con- 

 fluent or just separated by a narrow 

 neck, rarely quite separate ; c may 

 touch E or may be distinctly sepa- 

 rate ; D may be partially confluent 

 with E or narrowly separated. 

 Sternum mostly yellowish, the 

 sutures sometimes marked with 

 blackish. 



Western Scottish. (Male.) 

 Line extends downwards somewhat, 



as in vulgatum. 

 Humeral suture more heavily marked 

 with blackish. Narrow middle 

 field usually strongly outlined in 

 fuscous and divided by a broad 

 diagonal line, the two enclosed 

 spots (r, g) varying in size, but 

 the one nearer the stigma always 

 smaller and triangular. 



Note. — Even in an otherwise 

 very dark example, the infuscated 

 outline of the middle field is slight 

 and the diagonal division hardly 

 marked. 

 Spots A, B, c, D, e variable, but all 

 much reduced in size, and in the 

 Mallaig examples never confluent. 



Sternum mostly blackish posteriorly, 

 with a yellowish oval marking on 

 either side of the middle line, these 

 markings diverging caudad and 

 having a yellowish tail (the black 

 condition is no doubt in part the 

 result of age). 



B 2 



