228 THE E^^TOMOLOGIST'S RECORD. 



EXPLANATION OF PLATE V. 

 Larv^ of Acronvctas in First Skin. 



Fig. I. — Acronycta ( Viminia) auricoma. Larva in first skin fed a little X 20 diam. 

 Fig. 2. — Acronycta ( Viminia) auricoma. Larva full fed in first skin x 12 diam. 

 Figs. 3 and 4. — Acronycta {Viminia) mcnyanthidis. Larvae partly fed in first skin 



X 24 diam. 

 Fig. 5- — Acronycta { Viminia) myriciv. Larva full fed in first skin, indeed close upon 



first moult X 22 diam. 

 Fig. 6. — Acronycta ( Viminia) venosa. Larva fed a very little in first skin x 34 



diam. 

 Fig. 7. — Acronycta ( Viminia) nimicis. Larva half fed in first skin X 27 diam. 

 Figs. 8 and 9. — Acronvcta [BtMilcia) ligiistri. Larvce well fed in first skin x 22 diam. 

 Fig. 10. — Acronycta [Cuspidia) aceris. Larva in first skin newly hatched X 30 diam. 



MELANISM AND MELANOCHROISM IN BRITISH 

 LEPIDOPTERA. 



By J. W. TUTT, F.E.S. 



{Contimied from page 172.) 



Tt has been suggested, and I have known it assumed as fact, 

 ^ that exposure to cold frequently darkens the colour of cer- 

 tain double-brooded species of lepidoptera, and have seen 

 Selenia illustraricx brought forward to illustrate the assumption. 

 But, if cold could aid, in any way, the production of melanic 

 forms, why, in Britain, do we get our most melanic forms on 

 the west coast of Ireland, where, owing to the influence of the 

 Gulf Stream, the temperature is, for the latitude, exception- 

 ally high ? It is also a matter of fact, that species from dry 

 open areas in the high latitudes of America and Europe 

 present no traces of melanism. 



The first writer on the subject of dark coloration being pro- 

 duced by a low temperature, was Professor Weismann. To 

 me, his experiments, so far as lepidoptera are concerned, 

 appear of little or no value. The incidental influences of 

 moisture, etc., appear to have been overlooked entirely, and 

 his experiments were too general to be of much service. Mr. 

 Merrifield has been paying considerable attention to the influ- 

 ence of temperature on seasonably dimorphic species, and his 

 general conclusions {Transactiotis of the Ent. Sac, 1889, pp. 

 78-97) are of much greater value. Professor Weismann prin- 

 cipally directed his attention to the application of a low 

 temperature to the pupa, and considered, that retardation in 

 this stage, was the principal factor in producing a dark colo- 

 ration in a winter form of a double-brooded species, where 



