THE ANNALS 



AND 



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 Frederick M'Coy, Professor of Geology and Mineralogy 

 in Queen's College, Belfast. 



The class Crustacea having received less attention from British 

 palaeontologists 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. Podophthalma. Tribe Decapoda. 



(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 Pilumnus 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 (0. Labechii of Desl. Mem. de la Soc. Linn. 



Ann. $ May. N. Hist. Ser. 2. Vol. iv. 11 



