268 Deceinher, 



tsoutheni brown form. The nearest approacli to this is in two specimens such as I 

 took at Cannock Ciiase in June, with white ground dusted with brownish, and very 

 pretty, complete, liglit brown markings. These were taken on May 25th on larch 

 trunks at Grrange-over-Sands, Lancashire ; and with them a similar specimen, but 

 devoid of the usual conspicuous dark blotch beyond the middle of the fore-wings, 

 another very white and with faint markings, and two considerably dusted with dark 

 smoky-bi-own. These Mr. Day had, very naturally, placed in his collection as T. 

 crepuscularia. The other series (biundularia) consists of seventeen specimens, all 

 from Delamere Forest, all very dark smoky-grey or blackish, or varying in that 

 direction. One is of a smooth smoky-blackish without markings, except that the 

 subterminal white line is distinct on all the wings, it is the blackest of the series, 

 and was taken on March 31st, 1893 ; another, the palest of the series, smoky-white, 

 abundantly dusted with smoky-grey, and showing the usual markings in black-brown, 

 was taken on March 23rd of tins year. The other fifteen are intermediate between 

 these two, and very much alike, excessively suffused with a dusting of smoky-black, 

 but all showing the usual markings in some degree ; eight were taken on April 26th, 

 1893, the rest in May of the present year. Tliese dates, in connection with the 

 characteristics of the specimens, should be carefully noted. Surely it is not reason- 

 able to base distinctness of species on mere dates of appearance in tlie face of such 

 results as these? And surely, if it were not already done, Mr. Robson's evidence 

 would sweep away the myth of single-broodedness in one form as against double- 

 broodedness in the other! Should this be conceded, the fact of a curious form of 

 dimorphism existing in this species would seem to be established, and the evidence 

 of distinctness would appear, to my judgment at any rate, to have arrived at an 

 " irreducible minimum," namely, the ipse dixit of those who say " I will undertake 

 always to separate the two species." — Chas. G-. Baeeett, November 4:th, 1896]. 



SILVAN US SURINAMENSIS (Linn.). 

 BY G. C. CHAMPION, F.Z.S. 



Several closel}^ allied species are confused under this name in 

 collections, and as three of them are cosmopolitan it may be useful to 

 call the attention of British Coleopterists to the subject. At present 

 I have only been able to detect one species, S. surinnmensis, in British 

 collections ; perhaps others may be more fortunate, as S. mercator, and 

 perhaps S. bicornis, are certain to be found here eventually. S. 

 mercator has recently been identified in North America.* The follow- 

 ing Table is chiefly taken from M, Guillebeau's " Note sur les Silvanus 

 du groupe de sitrittamensis " [Rev. d'Ent., ix, pp. 220-223 (1890)]. 

 The sexual characters of S. surinamensis do not appear to have been 

 noticed by British writers. 



o. Temples (the cheeks or post-ocular portions of the head) long, equalling two-thirds 

 of the diameter of the eyes ; thoracic grooves equal. 



* cf. Chittenden, Canad. Entom., xxviii, p. 197 (August, 18961. 



