68 



to be a distinct species : with all respect for Tutt's powers of obser- 

 Yation, one cannot but consider that in this case he acted without 

 properly considering the matter, as there is not the slightest doubt 

 that these two forms are one and the same species, and certainly so 

 in the colony from which he took the specimens that he named 

 hippocreiiidix. I have examined a number of specimens from his 

 series, and they are a rather small race with the sixth spot weakly 

 developed. If taken alone they might be thought to be a species in 

 a genus where the species, although being quite distinct, show a 

 marked superficial resemblance ; but other colonies fail to show the 

 characteristics noted by Tutt, although they correspond exactly to 

 the true fiUpendulae. Furthermore, the larvae of both are identical; 

 the appendages are not to be differentiated, and finally they pair 

 readily, the result always proving fertile in the first and subsequent 

 generations. It often happens in the localities where true filipendulae 

 occurs that an odd specimen will emerge in May, and on the ground 

 where tutti occurs it is sometimes possible to find belated examples 

 a month or six weeks after the brood is over. If true I'dipendulae 

 are fed on the succulent marsh form of Lotus they grow to a larger 

 size before hibernation than if fed on Lotus cornicidatus, feed for a 

 shorter period after, and the imagines emerge several weeks before 

 the proper time of emergence. This appears to be conclusive that 

 tutti and filipendulae are one and the same species. In fairness to 

 Tutt, one can only say that in trifolii the early form always appears 

 on the chalk hills, and the late brood on marshy ground. Like tutti 

 and filipendulae, trifolii and palustris will pair quite readily, but in 

 this case the late form is very much larger, so that it is possible 

 that in one case the more succulent food causes a more rapid growth, 

 and in the other it causes, after a prolonged period in the larval state, 

 a larger and heavier insect. 



The Zygaenas show considerable variation, but the same general 

 type of variation runs through the whole genus. First of all we 

 have the various forms of colour : with one or two exceptions the 

 normal colour of the forewings is green or blue-black with spots or 

 bands of scarlet or crimson, and the hindwings of the same colour 

 with a margin of blue-black in varying depths. It is of fairly 

 frequent occurrence to find the crimson spots and hindwings changed 

 to pink and the blue-black of the forewings slatey blue; this is 

 generally accompanied by some degree of malformation, so that 

 possibly this form may be the result of some injury to the pupa. 

 The red colour on occasion changes to orange or lemon yellow : this 

 form may occur anywhere, and is a recessive, and possibly if this 

 was analysed from the Mendelian point of view, it would be found 

 to be a red from which the factor for intense colour has been 

 eliminated. In the other direction the normal colour may be in- 

 tensified, becoming black through varying shades of brown ; this 

 also is a recessive, and probably is a red to which an additional factor 



