operated to render many insects extremely scarce that were 

 once common around London, but it is scarcely credible that 

 many Lepidoptera could have been overlooked formerly, 

 which now are by no means rare ; may we not therefore infer, 

 that some species, which under ordinary circumstances are 

 produced very sparingly, may be multiplied, under favourable 

 incidents, to a vast extent : for it must be remembered that we 

 meet comparatively, with but few of those that exist, and it 

 requires considerable broods probably to throw a single spe- 

 cimen in the way of the collector : when, therefore, any species 

 is found extensively, the production of it must have been very 

 abundant. I am led to these remarks by the fact, that two 

 species of this group have been discovered in Great Britain 

 within a few years: one, the Arctia ccenosa (pi. 68, which is 

 very rare in Germany and seems to be unknown in France 

 from Godart making no mention of it) ; the other, now under 

 consideration, appears to be unnoticed by any author. 



The texture of the wings is between that of ./4. ccenosa and 

 A. clirysorrhcea^ but the superior are differently formed from 

 either; the male of the latter has a tuft of hair at the apex of 

 the body, but it is very short. The minuteness, if not the ab- 

 sence of the palpi and maxillffi (which in the genus Arctia are 

 quite visible to the naked eye) will justify the step I have 

 taken in constituting the genus Arcturus. 



The male figured was captured by Joseph Sparshall, Esq. 

 in a lane near Horning, early in the morning of the 7th of 

 August 1829; it was resting upon the trunk of an elm-tree 

 he believes. 



It gives me the greatest pleasure to dedicate this insect to 

 one of my earliest and most esteemed friends; and the zealous 

 desire to forward science which he evinced on a former occa- 

 sion, when he deposited in the British Museum the only au- 

 thentic specimen of one of our finest moths (the Odonestis 

 Pini\ has again manifested itself by his enriching my collec- 

 tion with the addition of this rare and singular insect. 

 The plant is Brassica campestris (Field Cabbage). 



