Insects. 



(5211 



* Zoologist ' that they should he made fully aware of the grounds upon which Pulyom- 

 matus Agestis and Artaxerxes are considered one species, as there seeins to be still a 

 considerable-amount of scepticism upon the subject : I must beg leave, therefore, to re- 

 capitiilate a little. In the first place, there is no appreciable difference either in struc- 

 ture or markings ; the differences being absolutely limited to the colour of the discoidal 

 spoi on the upper side, and the greater or less distinctness of the pupils to the ocelli 

 beneath. Every good naturalist knows that colour, unaccompanied by difference of 

 structure or marking, is of very little value in the discrimination of species ; and if we 

 admit it in this instance, we must also consider the Scotch variety of Coenonympha 

 Davus as a distinct species, along with many other Scotch insects which differ 

 in colour from the same species as found in the South of England. Secondly, 

 the description of the larva of Agestis will serve also for that of Artaxerxes or 

 vice versA. Although I have not yet seen the larva of Agestis alive (the larva? 

 forwarded by Mr. Harding having been those of Hypera fasciculata, and one true 

 Agestis larva which Mr. Doubleday kindly sent me having produced several Micro- 

 gaster cocoons on its way here), I have seen a beautiful drawing of the larva of Agestis 

 by Mr. Standish, which Mr. Doubleday kindly sent me; and, as far as one can judge 

 from a drawing, the two larvae are the same. Again, the larva of Agestis can 

 no longer be said to feed exclusively on Erodium, if indeed this is its usual food-plant, 

 Mr. Gregson having found it on Helianthemum, which, added to the obesrvations of 

 Mr. Walker (Zool, 6248), leaves no room to doubt that Agestis is at least as 

 much attached to Helianthemum vulgare as it is to Erodium cicutarium. The 

 habits of the two with respect to pupation are also essentially the same ; as though 

 Artaxerxes when near the base of a rock, or when confined in a box, sometimes fastens 

 its pupa by a silken thread across the body, it does not always do so, and the pupa is 

 frequently found on or in the earth beneath the plants. Although a matter of 

 secondary importance, I may mention that the little white cocoons of Microgaster from 

 the Agestis larva belong apparently to the same species as that which infests the larva 

 of Artaxerxes. Mr. Crewe says that he is " an utter unbeliever in what are called 

 permanent varieties or races." He surely does not mean this to apply to the whole of 

 nature ; and if we have permanent races in the human species, in many of the higher 

 animals, and in other orders of insects, I do not see why they should not exist also 

 among the Lepidoplera. The conviction that they do so exist is becoming every year 

 more strong with me ; and I believe that not only are modifications in colour, size, 

 &c., frequently hereditary, but also variations in habits ; and this in cases where there 

 can be no reason to doubt the identity of the species, or to suppose that the facts tend 

 to support the theories of Lamarck. — R. F. Logan ; Diuldingstoriy Edinburgh, 

 October 13, 1858. 



[Is not the supposition that Polyommatus Agestis feeds on Erodium a mere mis- 

 take, arising from an individual larva having accidentally been found by Professor 

 Zeller wandering from its food-plant ? — E. Newman.'] 



Polyommatus Artaxerxes and Agestis. — When I wrote a reply to My. Logan's 

 paper, in the June number of the 'Zoologist,' I hoped that it would have produced 

 some fact to prove that the two species were one and the same, but it appears thai those 

 parties have no fact to produce. Mr. Newman certainly has made a mountain of a 

 mole-hill regarding my mistake, and has it seems quite forgotten the main question, — 

 are the two species one and the same? Yes, says Mr. Newman, I had that opinion 

 twenty -five years ago ; and it appears that since that period he has not taken cue step 



