324 BRITISH LEPIDOPTERA. 



appears to be the oldest name that covers the great mass of the Fumeas 

 in British collections, and often called without much apparent reason, 

 roboricolella, nitidella, intermediella and even crassiorella and crassico- 

 lella. Chapman says that the definite character that unites all these 

 forms is the length of the anterior tibial spur, which measures from 

 •77 to "81 the length of the tibia. The antennal joints vary from 16 

 to 20 and the wing expanse from 9mm. to 15mm. There is consider- 

 able variation in wing form, generally there is a good breadth basally, 

 by the inner margin commencing at the base with a deep rounded 

 lappet, and the inner and costal margin making some approach to 

 parallelism, but not a few of those examined show a considerable 

 approach to the form of M. mitfordella, and it is very probable that by 

 measuring the spurs of a number of these some would prove to be 

 really that species. The various races of F. casta are exceedingly puzzling 

 and it appears probable that each colony of the species is fairly well- 

 defined (probably due more or less to in-breeding), and does not present, 

 except as aberrations, specimens agreeing with the forms from other 

 localities, and it becomes a matter of little moment as to whether one 

 should call the different races species or not. Chapman further notes 

 that the only ground for doubting that they should be all called one 

 species is that there is some basis for believing that the casta and 

 intermediella forms do occur together in some localities, and yet main- 

 tain themselves as separate races, a matter that certainly requires further 

 investigation. The forms and races of this species differ slightly in 

 size, as also in the number of antennal joints. We have assumed the 

 small, most common, and, perhaps, constant race to be casta, the larger 

 and more variable one inter mediella, Bruand. Warren observes that 

 ? examples from Wicken Fen appear to have the anal tuft con- 

 spicuously paler. The various forms may be diagnosed as follows : 



a. Typ. form casta, Pall. — Exp. al. 11mm. -12mm. ; antennal joints 18. This 

 is a very definite race, and appears to be the most common and widespread form. 

 I am by no means prepared to assert that this form is not a true species and distinct 

 from the next form, only, if so, I cannot divide them with even approximate confi- 

 dence (Chapman). 



(3. var. inter mediella, Bruand. — Exp. al. 13mm. -14mm. ; antennal joints 18-20. 

 This is rarer than the last form and it is, in places, apparently a distinct race, in 

 others merely an aberration of casta. Some of the largest specimens have only 

 18 antennal joints, and some of the smallest 20, so that I feel unable to divide the 

 forms casta and intermediella into two distinct species, defined as — casta 18 

 joints, intermediella 19-20, though I am prepared to grant that this may be so and 

 that the variations in size are such a? to make them overlap in this feature. In 

 casta and intermediella, the antenna? present indications of being in process of alter- 

 ing the number of joints, for at the base there is sometimes a third (1st of clavola) 

 without pectinations, in others the 1st and 2nd of clavola are joined together in one 

 long joint, carrying two pairs of pectinations. At the tip again the typical arrange- 

 ment is for the last joint to be simple and the preceding one to carry two pectinations 

 of nearly its own length, but the last (unpectinated) joint may be very small and in 

 some examples is quite wanting when the then terminal joint carries two pectina- 

 tions (Chapman). 



7. ab. minor, Chapman. — Exp. al. 9mm. -10mm. ; antennal joints 18 ; wings 

 often more diaphanous than type. This is called an aberration rather than a variety 

 as it occurs in odd specimens in different collections, and is usually probably a 

 starveling form, rather than a distinct race (Chapman). 



3. var. howerella, Chapman. — This is a very definite form in one special 

 respect, and has been met with only in a certain number of specimens bred by Mr. 

 B. A. Bower from Kentish localities. The general facies is much that of the typical 

 form casta (nitidella), if anything it is rather smaller, being 11mm. in expanse, with 

 anterior tibial spurs distinctly over -77 of the length of tibia, dark in colour (being 



