306 Miss Cora B. Sanders on the Ixhopalocera 



greater than we ventured to hope for at the outset of the 

 enquiry. 



I have claimed that the Burchell Collection, with its 

 numberless accurate data, is of the highest historic importance 

 in enabling us to carry back " the detailed record of the occur- 

 rence of many thousands of species in two most interesting 

 parts of the world, and to construct a trustworthy standard by 

 which to measure the rate of future change" (Ann. & Mag. 

 Nat. Hist., Jan. 1904, p. 46). The trustworthiness of the 

 standard depends upon the persistence of the data unaltered 

 from Burchell's time to this. There is, fortunately, the means 

 of checking these data by comparison with a list of the Brazilian 

 Arthropoda made under Professor Westwood's direction 

 during the years which immediately followed the gift of the 

 collection in 1866. A second list of the dates of every indi- 

 vidual of a species in Professor Westwood's handwriting is 

 found on one specimen of many species, and this has often 

 been a valuable check upon the complete list when errors 

 were suspected. 



The first section of the butterflies is written in Professor 

 Westwood's own handwriting, and deals with the Heliconiidge 

 in the old broad sense, comprising the Ithomiinae, the genera 

 Lycorea and Ituna of the Danainas, and the Heliconiinas. 

 Although in the form of rough notes and very difficult to 

 disentangle, it is a model of accuracy. It records the whole 

 of BurchelPs notes written on the labels accompanying the 

 specimens, but apparently none of the facts to be found in 

 his manuscript note-books. Beyond the Heliconiida? the list 

 of butterflies is continued in an extremely clear handwriting, 

 with great neatness of arrangement, but containing occasional 

 slips and mistakes which can be detected by careful comparison 

 with the existing data. It is evident that Professor Westwood 

 arranged the vast mass of material into groups and sub- 

 groups, and in each of these separated the forms into what he 

 believed were distinct species. An assistant employed under 

 his direction then copied the notes written by Burchell on the 

 labels attached to each specimen. In some cases Westwood 

 himself added names to the forms thus grouped together in 

 the list ; but in the vast majority of cases the list remains 

 as it was written by his assistant. My inference from the 

 handwriting has been kindly confirmed by my friend Miss 

 Swann, who tells me that her uncle, Professor Westwood, 

 employed an assistant to write for him about the time at 

 which these lists were copied. The backs of old University 

 Notices were employed for this purpose, and a rather valuable 

 record of the acts of the University during some of the years 



