16 [■'"""^' 



of Dytiscus latissimiis within onr faunal limits. This species was added by Mr. 

 Crotch to the " check hst," on information furnished by Dr. Sharp. I subsequently 

 protested against the addition of this or any other European species to our list, 

 unless on well authenticated evidence. In times past it was a common occurrence 

 to have European species sent me from Canada, under circumstances admitting of 

 very little doubt of their foreign origin. It is, of course, possible for a species oc- 

 curring in our fauna to reach a Eui'opean student before being seen by us here ; but 

 I think it extremely unlikely that one so large as the species above quoted would 

 reach Europe before falling under our notice. After reading Dr. Sharp's almost 

 crushing remarks on my protest, it will be well to go twice over his penultimate 

 sentence — " The evidence of the existence of this remarlcalle species in North America 

 is, hoioever, undoubtedly in need of confirmation.'" — GrEO. H. Horn, Philadelphia, 

 U. S. A. : April, 1879. 



On the cocoonsformed hy Kypera riimicis and its parasites, and Ciomis scrophuIaricB. 

 — Some observations from the " Address of the late President of the Entomological 

 Society of London, on the 15th January, 1879," quoted in the March number of this 

 Magazine, p. 240, have induced me to suppose that the following notes may not be 

 unacceptable. In Westwood's " Modern Classification," vol. i, p. 343, it is stated 

 t,bat — •" The larvae of the genus Hypera form small oval cocoons, like gauze, composed 

 of loose threads, permitting the larvce or pupte to be seen through the meshes, and 

 attached on the under-sides of various leaves, &c." On the same page, speaking of 

 Cionus, it is said : — " Schiiffer has figured the transformations of the C. scrophularics 

 (Abhandl., vol. iii, pi. 9), under the name of " der Kropf krauts Eussel-kafer." The 

 cocoon is formed with open meshes, like that of the Hyperce. 



As far as regards the cocoons of M. rumicis, I have found them as frequently on 

 the upper as on the under-side of the leaf In one instance I found four cocoons 

 attached underneath in the space of an inch and a half along the angle of the mid- 

 rib where the parenchyma had been eaten away, and only a rusty network of nerves 

 and reddish epidermis remained, exactly matching the cocoons in colour and appear- 

 ance. I was much struck also with the resemblance of the cocoons on the upper 

 surface to those rusty stains so common on the leaves of the various species of Rumex. 

 These stains are circular, consisting of an outer broad brownish-red margin and a 

 central paler yellowish disc. Now, as the cocoon is a globular reddish net-work, it 

 necessarily looks darker on the circumference where the meshes are massed together ; 

 but besides this, the contained larva, being lighter, especially on the ventral side- 

 yellowish, or dirty white — imitates the lighter centi'al disc of the dock-stain. It 

 would not be safe to infer that all, even striking, resemblances are necessarily cases 

 of imitation or mimicry. On the other hand, as by far the greatest number of the 

 objects in the field of vision at any moment are not seen in the macula lutea, or point 

 of most perfect sight, very superficial resemblances may afford very efiicient protection. 

 If the general effect on the eye is the same, and if the thing imitated is very much 

 more common than the thing imitating, the protection is good. Both these conditions 

 are present in the case of the Hypera cocoon. Cionus scrophularicB also in shape, 

 size, and colour, and in its relatively large, circular, black dots, very much resembles 

 the flower-buds of its food-plant, among which it is generally to be found. It is true 

 it has two of these black dots for the flower-bud's one, but so situated that only one 

 of them is usually seen at once. Mr. Eye has noticed (" British Beetles," p. 195), a 



