On Fossil Arthropods in the British Museum. 273 
rarispinus, plate 23, fig. 1, area I. This is an external sand- 
stone mold of the ventral side seen from above, and is there- 
fore reversed, as is your specimen of Pholidocidaris anceps 
seen from within. 2 
“‘T found in the great preponderance of cases in Paleozoic 
Hehini that odd-numbered columns, while starting in the 
centre, passed upwards to the left of the centre. On the other 
hand, even-numbered columns usually start on the right of 
the centre and maintain that position throughout their extent. 
Such being the case, I feel that such is the probable course in 
any given specimen until it proves itself exceptional. 
“This internal and external view business and molds of 
exterior and interior seen in reverse are the most confusing 
things to keep true orientation straight in that I ever 
tackled.” 
XXXVI.— Fossil Arthropods in the British Museum.—I. 
By T. D. A. CockEre.L, University of Colorado. 
Tue British Eocene insects hitherto described consist of three 
species of Coleoptera, one of Isoptera, and one of Odonata. 
The two latter, published in recent years, are in the British 
Museum. Dr. F. A. Bather has kindly transmitted to: me 
the undescribed Eocene material belonging to the Museum, 
and included with it I find the type-specimens of two of the 
already-named Coleoptera. These were figured by Westwood 
in 1854, without names; in 1856 names were supplied by 
Giebel. | 
In the present paper I complete the account of the Hocene 
material, aside from the Coleoptera, which will be discussed 
separately. Six species are described, more than doubling 
the list, and adding three orders. The ants are the oldest 
Old-World species. ‘The Fulgorid represents a type of 
broad-winged moth-like Homoptera, well developed to-day in 
the Oriental region, but especially prominent in the Hocene 
fauna of the Rocky Mountains, as I shall show in a paper 
now awaiting publication. So far as can be seen, the Hnglish 
insect belongs to one of the American genera. The most 
remarkable find, however, is a large wing belonging to the 
Mesozoic family Pseudosiricide. Its discovery is almost as 
startling as that of a Tertiary dinosaur; but after careful 
study I cannot separate the species from the Mesozoic group, 
and, indeed, it is ‘very close to the genus Formicium. 
Ann. & Mag. N. Hist. Ser. 9: Vol. v. 19 
