FROM GURNET BAY, ISLE OF WIGHT. 349 
This form resembles our fossil in the small size of the cephalon 
and the broadly-expanded recurved character of the margin of the 
anterior segment, in the form of the eyes, the antenne, and the poste- 
rior pair of limbs; but the abdominal shield is larger in the fossil. 
Dr. Kinahan obtained Sph. serratum in the River Logan, Belfast, 
and inthe River Dodder, Dublin *; so that the fossil species occur- 
ring in this fluvio-marine bed is quite in accord with the habits 
of its modern congener. 
I subjoin a brief notice of Archwoniscus Brodiet by Prof. Milne- 
Edwards, who writes? :— 
‘The specimens which I have received from Mr. Brodie (disco- 
vered in the Wealden [sic] [Purbeck] formation, in the Vale of 
Wardour, Wiltshire) are 12 centimetres ¢ in length and 9 in breadth; 
but this geologist has found some whose dimensions are much 
greater.” [I subjoin the measurements of several specimens pre- 
sented by the Rev. P. B. Brodie to the British Museuam— 
Length. Breadth. 
2 rmalllamig a paths 4). 4 sek 8 millims. 
IPAS? (Ria ana Ei gs EATS AE Ns 9 3 
Wg) i MISC i ala Astana urea nie ie Be 
20 BS ed Tie SCR Cra Fas Tea Vesey 
‘The body is very smooth, and composed of a series of rings ter- 
minated posteriorly by a rounded shield. Unfortunately the head 
is not well preserved in those specimens which I have examined. I 
have not been able to discover any traces of the legs ; but Mr. Brodie 
has detected them in some of his specimens. I have been able to 
make out traces of the antenne. The fossil is evidently an Isopod, 
and from its general form should be arranged in the family of 
Cymothoide, but it cannot be referred to any known genus. It 
appears to be intermediate between Sevolis and the errant Cymo- 
thoide. It resembles the former in the greater development of 
its body-segments, especially of the epimeral portion of the segments 
as compared with the tergal portion, and also in the expansion of the 
epimera and the position of the terminal shield of the body. 
“Tt ditfers from Serolis by the greater development and mobility 
of the anterior rings of the abdomen—characters which ally it to 
Afga and other errant Cymothoide. ‘The several rings between the 
head andthe caudal shield scarcely differ from one another, so that 
there is no visible limit between the thorax and the abdomen ; but 
one can count as many as twelve; and as the number of thoracic 
rings never exceeds seven in the Edriophthalmia, we must conclude 
that the remaining five most posterior ones belong to the abdomen, 
which would consequently be composed of six movable segments, as 
* Bate and Westwood, Hist. Brit. Sess.-eyed Crustacea, 1868, vol. ii 
pp- 405-407. 
t ‘Annales des Sciences Naturelles,’ 2¢ série, 1843, tome xx. Zoologie, p. 327. 
¢ [For “centimetres” read “millimetres.” This error occurs throughout 
Milne-Edwards’s paper. I have the specimens of both Archzoniscus Brodiei 
and Palgoniscus Brongniartii before me; it is evidently a clerical error. ] 
Q. J. G. S. No. 138. 2B 
