Metrick. — Revision of New Zealand Notodontina. 249 



been greatly increased, and therefore, in view of Mr. Prout : s proposal, I 

 made a new examination of all the species which I have included under 

 Xanthorhoe from all regions, and noted the following points :• — 



(1.) Every intermediate stage is found between these two types of struc- 

 ture, distinct as they may appear in extreme forms. The outward angula- 

 tion .if the lower part of the transverse vein depends solely on the postion 

 of 5 as a concomitant variation : if 5 rises much below the point of junction 

 the angulation is pronounced ; if from near below, the angle is difficult of 

 perception ; and in some species 5 so closely approaches the point of junction 

 that they can be classed in either category. 



(2.) Insistence on this character would in repeated instances involve the 

 separation of species which in all other respects appear to be closely and 

 truly related together. For example, cinerearia would be a Larentia and 

 semisignata a Xanthorhoe, as correctly noted by Mr. Prout. Now, these, 

 though so similar as to have been long thought identical, are perhaps not 

 so very closely related, having some difference also in antennal pectinations 

 and shape of wing ; but plumbea is so similar in all respects to cinerearia 

 as to be nearly indistinguishable, agreeing with it exactly in all those 

 characters of size, antennal pectinations, and shape of wing in which semi- 

 signata differs ; and yet plumbea would be an undoubted Xanthorhoe. Again. 

 beata, benedicta, and adonis must be admitted by every New Zealand ento- 

 mologist to be exceedingly closely allied. Now, frmtaisan obvious Larentia, 

 with 5 rather widely remote from the point of junction ; in benedicta, it is 

 less remote, but still well separated in general (though I have an example 

 in which one wing would pass for Xanthorhoe) ; whilst in adonis 5 is some- 

 times barely separate, but in general practically indistinguishable from 

 normal Xanthorhoe, the transverse vein being straight, without either 

 inward or outward angulation, and 5 rising from just by the lower end of 

 the discal spot ; similarly chorica, which is certainly more nearly related 

 to these three than to any other, is quite as adonis. Again, consider 

 the group of nearly related species 113-123 : frivola and helias would be 

 Xanthorhoe, recta would be Larentia, dionysias would be Xanthorhoe, aegrota 

 to sericodes would be Larentia, nephelias would be Xanthorhoe. If nephelias 

 is not closely related to sericodes, what is it related to ? 



(3.) Having grouped, as well as might be, all the species under the two 

 heads of Xanthorhoe and Larentia, I considered the groups thus formed, 

 to see if they had any characters of homogeneity as wholes, and it appeared 

 that they had not : there was no other structural or superficial character 

 which distinguished or belonged to one genus as compared with the other ; 

 nor was there any geographical support to the distinction, for both genera 

 occurred indiscriminately in all regions. 



(4.) Precisely the same variation of structure occurs in other allied 

 genera, such as Hydriomena and Notoreas, and even in small genera 

 such as Asaphodes. It must, therefore, either be a basic and primitive 

 distinction, in which case all these genera must be thrown together and 

 redistributed on this as a primary base (which is apparently not proposed 

 by any one, and would confuse affinities to a degree far exceeding that shown 

 above), or the particular modification of structure must be liable to arise 

 independently in a number of instances : there is no other alternative. If 

 the second of these alternatives is (as it appears) not disputed, there can be 

 no reason why the modification should not arise independently in different 

 parts of the same genus, as well as in different genera ; and if that can take 

 place the character is a bad one, and cannot be used for systematic purposes 



