( xxix ) 



zoologists decides in a contrary sense. It is sometimes stated 

 that the generic names of the ' Verzeichniss ' are nnaccom- 

 panied by diagnoses, but this is not so ; the characters used 

 are, it is true, often based on markings only, but they are 

 really diagnostic, and, in fact, more scientific than those of 

 many later writers who have pretended to draw up structural 

 definitions, which, after all, defined nothing. It must be 

 remembered that the ' Verzeichniss ' is analytical, the generic 

 definitions consisting, in fact, not only of the characters 

 immediately prefixed to the genera, but also of the others, 

 defining each of the ^_iumerous divisions and subdivisions 

 under whose heading che genus falls. " I refrain, then, 

 from pointing out t inconsistencies and errors in Prof. 

 Eadcliffe-Grote's crit ans, because I reject the main assump- 

 tion on which the cri isms are based. He must convince me 

 that these names of loubtful value, doubtful date, doubtful 

 publication, but undo ibtedly undefined, are good, before I 

 need discuss the appar ation of them." 



Prof. Meldola b.c^tf^d that there were two papers to be 

 read, but that the T ctsurer had given notice of a subject 

 for discussion, and ' '^ would ask him to introduce his subject 

 first. It Avas " A jussion as to the best means of pre- 

 venting the extin' u of certain British Butterflies." 



Mr. McLachlan sait that so long ago as 1893 he chose the 

 subject of the decadence of British butterflies as a subject for 

 a Presidential Address to the West Kent Natural History 

 Society. The rema ks he then made were published in 

 the " Entomologist's Monthly Magazine" (June, 1893), in a 

 somewhat abridged form , and be thought a good many pre- 

 sent would remember the fact. He took it for granted that 

 British butterflies were on the downward scale. It was 

 certain that in the neighbourhood of London many butterflies, 

 common about the year he was born, or earlier, had become 

 extinct. "VN''ithin the last fifty years, he thought three of our 

 British butterflies — CJiri/sophanUK disjxtr, Lycana acis, and 

 Aporia craUcyi, had almost, if not entirely, disappeared. The 

 species, being weakened by some circumstances or other, were 

 unable to 1 Id up against a bad season or a series of bad 

 seasons, anu so disappeared. There were suspicions gener- 



PROG. ENT. SOC. LOND., IH., 1896. D 



