THANATITES VETULA. 65 



distance from it, one in each interspace. Length of fore wing, 14""°-; length of 

 hind wing, 13-65""" ; extreme breadth of hind wing, 11'25™"'-. 



The smgle fossil represented by von Heyden under the name of Vanessa vetula, 

 is preserved on a greasy, dark brown, thin and exceedingly fragile sheet of "brown 

 coal," and is likely to become so aflfected by weatheiing as to be almost or quite 

 indistinguishable in the course of time. Indeed it is excessively obscure at the 

 present tune, and no fossil object I have ever studied has proved so difficult to de- 

 cipher as this. It represents an insect (PI. Ill, fig. 12) lying upon its side in a 

 somewhat natural attitude (compare fig. 11), so that one can see the whole of the 

 under surface of the left hind wing, the costal quarter of the under surface of the 

 left fore wing, and a little more than a quarter of the upper surface of the right 

 fore wing, also of the costal area; the thorax and head with the eyes, the denuded 

 palpi, the partially unrolled tongue and fragments of the legs in a confused medley 

 may also be seen, but there is no trace of the antennae, nor of the right hind wing 

 (nor of the abdomen?). The left hind wing has an immaterial part of its outer 

 border removed, and a small portion of the outer border of the left fore wing is 

 also wanting, but the corresponding portion of the right fore wing is present. 

 The markings can only be made out by extreme care, and a very meagre portion 

 of the neuration, especially toward the borders of the wings, by great patience 

 and the closest examination; but most of what can be seen of the neuration adds 

 but very little to oiu* actual knowledge of the animal ; it simply adds its testimony 

 in the same direction as other features of the object. 



The illustration of von Heyden (PI. Ill, fig. 16) is faulty in several particiUars, 

 but this is not siu-prising when we consider the excessively obscure nature of the 

 fossil; it represents the insect as if the under surface of both wings of one side 

 were seen, the fore wing concealing a portion of the hind; a break in the stone is 

 taken for the outline of the wing (just above the extremity of the costal border of 

 the hind wing) and the markings of the two front wings are blended into one; an 

 abdomen is represented and above it an outline of the inner border of the hind 

 wing. The fossil has at first sight this appearance, but I think this view is errone- 

 ous, although on this point one may not speak with confidence, and it is compara- 



