THE ANNALS 
MAGAZINE OF NATURAL HISTORY. 
[SECOND SERIES.] 
No. 21. SEPTEMBER 1849. 
XIX.— On the Classification of some British Fossil Crustacea, with 
Notices of new Forms in the University Collection at Cambridge. 
By Freprricx M‘Coy, Professor of Geology and Mineralogy 
in Queen’s College, Belfast. 
Tue class Crustacea having received less attention from British 
paleontologists than perhaps any other of similar importance, I 
have put together in the following pages a few observations I 
have been able to make on the examples in the collection of the 
University of Cambridge, as well as on a great number of speci- 
mens of the same species, for the most part finely preserved, 
lent me by various friends to render my observations as perfect 
as possible. I have given descriptions of some of the best-marked 
new species, also of some new genera; I have endeavoured to refer 
some others, hitherto improperly placed in recent genera, to the 
various fossil genera established by foreign writers for cognate 
forms, and have ventured a few suggestions on the classification 
and systematic position of some of the groups. 
Class CRUSTACEA. 
Ord. PoporputHatmMa. Tribe Decapopa. 
(Brachyura.) 
Of this the most highly organized group of Crustacea, I believe 
the following genera have been quoted from British rocks with- 
out sufficient authority: viz. 1. Zantho (Leach); this has been 
quoted with doubt by Desmarest, Bronn, &c. from the London 
clay ; I have ascertained that the crustacea referred to are of an 
extinct genus, more nearly related to Pzlumnus than to Zantho, 
which I have named Zanthopsis. 2. Orithya (Fabr.): M. Des- 
longchamps referred with doubt a crustacean originally disco- 
vered by Sir Henry de la Beche in the greensand of Lyme Regis, 
to this recent genus of natatory Brachyura ; I find however that 
the species referred to (O. Labechii of Desl. Mém. de la Soc. Linn. 
Ann. & Mag. N. Hist. Ser. 2. Vol. iv. 11 
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