348 EH. WOODWARD ON EOCENE CRUSTACEA 
on each side a border formed by the epimeral pieces, which overlap 
one another and are of a quadrilateral form. 
“The abdomen is composed of two segments, the first of which 
resembles the thoracic rings and presents traces of a transverse 
suture ; the second is scutiform and semioval. Lastly, on each side 
of this terminal plate, one detects lamellar subfalciform natatory 
appendages, placed as in Spheeroma. 
“ From these peculiarities of structure, I am induced to believe 
that this fossil ought to be placed in the family of Spheromide ; but 
it does not sufficiently closely resemble any of the existing species 
in this group, and in the Museum I have classed it between Spheroma 
and Ancinus, and I have named it Paleoniscus Brongniartiz.” 
If to this we add Paleoniscus obtusus, Meyer*, from the Miocene 
of Bonn, which is, no doubt, closely related to the foregoing species, 
we have all the Tertiary forms hitherto described. 
The name Palconiscus, unfortunately, cannot stand, haying been 
preoccupied by Blainville for a genus of Fishes since 1818 (Paleo- 
miscum), and by Agassiz since 1833 (Paleoniscus). I would have 
suggested the substitution of Archwoniscus, Milne-Hdw., the name 
given to a fossil Isopod from the Purbeck of the Vale of Wardour ; 
but a reference to the figure (Pl. XIV. fig. 4), and to the subjoined 
description, will show at once that the relations of the four forms 
above enumerated are with the Spheromide, whereas the presence 
of several free and movable abdominal somites in Archconiscus con- 
nects it with the /Zgide and other errant Cymothoide. 
I would venture therefore to propose for these Tertiary forms 
the generic appellation of Hosphwroma. 
The known list of Isopod fossils will be then as follows :— 
Armadillo molassicus, Heer, ‘Primeval World of Switzerland, vol. ii. p. 5, 
fig. 210. Miocene, Giningen. 
Kosphzroma (Palzoniscus) obtusum, Meyer. Miocene, Bonn. 
—— (——) Brongniartii, Milne-Edwards. Lower Eocene, near Paris. 
—— fluviatile, A. Woodw. Upper Hocene, Gurnet Bay, Isle of Wight. 
—— Smithii, H. Woodw. 55 
Palega Gastaldi, Sismonda. Miocene, Turin. 
—— Carteri, H. Woodw. Grey Chalk, Dover. . 
—— sp. (Ferd. Roemer). White Chalk, with flints, Aalborg, Jutland, 
Denmark. 
Bopyrus (under carapace of Palgocorystes). Greensand, Cambridge. 
Archexoniscus Brodiei, Milne-Edwards. ower Purbeck, Vale of Wardour, 
Wiltshire. 
—— Hdwardsiit, Westwood. Lower Purbeck, Durdlestone Bay, Dorset. 
Engerchuris gigas, H. Woodw. Old Red Sandstone, Rowlestone, Hereford- 
shire. 
” ” 
Among the Spheromidz common to our coast at the present day, 
and also to that of France and Ireland, is Spheroma serratum, Fabr., 
sp. (see Pl. XIV. fig. 5). 
: 4 Palzontographica, Dunker und Meyer, 1858, Band y, pp. 111-113, t. 23. 
-0, 1,0. 
t See Quart, Journ. Geol. Soe. 1854, vol. x. p. 393. I regret to say I had 
overlooked the fact that Prof. J. O. Westwood had given a specific name to the 
specimen of Archgoniscus figured by him on pl. 14. fig, 12. 
