Hewett : Yorkshire Lepidoptera in igoo. 



8 3 



(b) Did distinctly melanic forms suddenly appear 

 and light forms become gradually scarcer? 

 Or, (c) Did the specimens of the district become, as 

 a whole, gradually darker year by year ? 



5. If the light forms have quite disappeared from the district, 



can you state at about what date they were last seen in 

 it? 



6. What are the conditions of the district as regards 



prevalence of smoke? Did changes in this respect 



take place at the time when melanism first appeared? 

 ia. In describing refer when possible to published figures in 



illustration of your description, and say how your 



specimens compare with these figures. 

 2A. Give actual numbers when possible, otherwise say whether 



' abundant,' ' fairly common,' ' scarce,' ' very scarce,' or 



• absent.' 



3A. If generally distributed in the district, it will be sufficient 

 to say so. 



4A. Whether at light, at sugar, bred from eggs, larvae, or dug 

 pupa?, resting on tree-trunks, stones, or otherwise. 

 This information may be sent either to Mr. W. Bateson, F.R.S., 

 Merton House, Grantchester, Cambridge, direct, or to Mr. W. 

 Denison Roebuck, F.L.S., for publication in 'The Naturalist.' 



In concluding these preliminary remarks, and in presenting 

 my readers with the report for 1900, I have great pleasure in 

 acknowledging the ready help I have received from so many 

 entomologists, both in supplying me with lists of their captures, 

 and in so willingly replying to all my inquiries respecting these. 

 As they can imagine, the task has not been a light one, but it 

 has to the author truly been a labour of love, and a very real 

 pleasure to help, in however infinitesimal a manner, to throw 

 a little more light on the distribution and natural history of 

 some of the species which inhabit the grand county with which 

 he and they are associated. What we especially require are 

 facts, an abundance of facts, and 1 would earnestly impress 

 upon all readers the necessity of keeping a diary of their more 

 important captures, with any interesting particulars relating 

 thereto, so that they may be available either for future years' 

 reports of this kind, or for a new edition of Mr. G. T. Porritt's 

 list of Yorkshire Lepidoptera, a work which, in the writer's 

 opinion, should be in the hands of all Yorkshire entomologists, 

 as also should a copy of this report and those of [89] and [897. 

 1901 March 1. 



