350 EOCENE CRUSTACEA FROM GURNET BAY, ISLE OF WIGHT. 
in Afga, Nelocira, &c. The sixth abdominal ring, which constitutes 
the terminal shield, is nearly semicircular, and presents on its median 
and anterior portion a tubercular swelling nearly analogous to that 
observed in the caudal shield of several Spheromide. Lastly, the 
structure of the head appears to be intermediate between that of 
these last-named Crustacea and that of which Serolis offers us an 
example; for the cephalic ring is enlarged, as in the Spharomida, 
while the eyes approach the median line, as in Serolis. 
‘“‘ From these facts one sees that this fossil Crustacean is perfectly 
distinct from all living Isopods, and ought therefore to be placed in 
a separate genus. I would propose to designate it Archwoniscus 
Brodie.” 
I have given an outline figure of this old Isopod in my plate 
(Pl. XIV. fig. 4). 
EXPLANATION OF PLATE XIV. 
Fig. 1. Hospheroma fluviatile, H. Woodw., 3 times nat. size. Upper Hocene, 
Bembridge series, Gurnet Bay, I. of Wight. , uropoda. 
Fig. 2. Hospheroma Smithii, H. Woodw., twice nat. size. Ditto. w, uropoda. 
Fig. 3. Hospheroma (Paleoniscus) Brongniartti, H. Milne-Edw. sp., “ Couche 
de Marne a Cytherées, sous les Marnes vertes.” U. Eocene, Butte de 
Chaumont, prés Paris. 3 times nat. size. w, uropoda. 
Fig. 4. Archeoniscus Brodiet, Milne-Edw. Lower Purbeck beds, Vale of War- 
dour, Wilts. 3 times nat. size. (The mesial line dividing the pos- 
terior somites in this figure appears to be due to the decortication 
of these segments, which has laid bare the cast of the straight ali- 
mentary canal.) 
Fig. 5. Spheroma serratum, Fabr.,sp. Recent British Marine and Estuarine. 
Fig. 6. Part of a slab of Bembridge stone, drawn of the natural size, covered 
with impressions of Branchipodites vectensis, H. Woodw. 
Figs. 7, 8, & 9. Portions of individual specimens, drawn with the camera and 
1-inch ebjective, showing—Or, br, branchial feet ; e, e, the eyes; 9, 9, 
the ovaries, with contained ova; c, c, the caudal somites, 
Fig. 10. Branchipus (Chirocephalus) diaphanus, Prevost. Recent freshwater, 
British. 
(Figs. 1-4 and Fig. 6 drawn from specimens in the Geological Collection 
of the British Museum.) 
Discussion. 
Prof. Woop-Masown stated that he was acquainted with three or 
four genera of Isopoda, members of which can live indifferently in 
salt and fresh water, one of them being the parasitic Bopyrus—tacts 
that seemed to indicate the process by which, in the course of ages, 
our fresh waters and, eventually, the land had gradually become 
stocked with mollusks and crustaceans, littoral and estuarine re- 
presentatives of these two classes of animals, which were ametabo- 
lous, having sufficient plasticity of their organism to enable them to 
withstand a gradual change from salt- to freshwater conditions. 
Mr. J. 8. Garpyer said that the beds belonged to the Bembridge 
formation, and that he had diligently examined the corresponding 
beds in the eastern corner of Whitecliff Bay, but had found them 
quite barren. No insects had been found in Alum Bay, and com- 
paratively few at Studland and Bournemouth. The Eocene insects 
found in England everywhere indicate a temperate climate. 
