542 MR. J. CAETEB ON THE 



45. On the Decapod Cettstaceans of the Oxfoed Clay. By James 

 Caetee, Esq., E.G.S., F.E.C.S., &c. (Eead June 23, 1886.) 



[Plate XYI.] 



The communication which T have fche honour to offer to the Society 

 relates to the Decapod Crustaceans of the Oxford Clay. It would 

 appear that the investigation of this class of fossils, as represented 

 in the British Middle Jurassic rocks, has been very incompletely 

 carried out. The number of species which have been recorded as 

 occurring in this country is very small, and scarcely any of those 

 which are known to occur have been figured or described in suffi- 

 cient detail for specific determination. Moreover, the bibliography of 

 the subject is extremely limited. As regards the Oxford Clay in 

 particular, the only species mentioned in the ' Catalogue of British 

 Possils,' published by the late Professor Morris in 1854, as 

 belonging to that formation is Mecochirus Pearcei, and the same 

 species is the sole representative contained in the very valuable 

 special ' Catalogue of British Fossil Crustacea,' published in 1877 by 

 Dr. Woodward, to whose persistent researches and numerous 

 publications so large a portion of all that is known on the subject is 

 justly attributable. Since the publication of his Catalogue, 

 Dr. Woodward has described and figured two new species, Mecochirus 

 Peytoniand Callianassa isochela, hoth. from the Ximmeridge Clay ; but 

 I am not aware that either of these forms has hitherto been found 

 in the Oxford Clay. In the recent most valuable edition of Phillips's 

 * Geology,' Mr. Etheridge states that Glyphea lej)fomana, G. Strich- 

 lancli, and Mecochirus Pearcei constitute the Macrurous Crustacean 

 fauna of the Oxford Clay ; and this statement is repeated and 

 confirmed in the works of most authors, with scarcely any additional 

 facts or information. Moreover, I have found most of the collec- 

 tions which I have had the opportunity of consulting to be com- 

 pletely barren of examples. 



Erom this paucity of evidence, and this general absence of 

 specimens from collections, it may be inferred that the remains of 

 Oxfordian Crustaceans are generally of rare occurrence. The 

 discovery, however, of a considerable number and variety of forms in 

 one locality of limited area proves that decapod crustaceans actually 

 did exist, and were somewhat abundantly represented during the 

 Oxford Clay period, and at the same time suggests the probability that 

 the absence of specimens in other localities has resulted from non- 

 preservation. The locality to which I refer is St. Ives, Huntingdon- 

 shire. Mr. Thomas George, E.G.S., who is at present engaged in 

 most useful work in the Museum of Northampton, has carefully 

 investigated the geology and assiduously collected the fossils of the 

 Oxford Clay as it occurs in that district, where it is quarried for the 

 purpose of brickmaking. He has obtained an extensive series of 

 specimens of Crustaceans which he has most liberally placed at my 

 disposal for description ; and these, together with the examples in 

 the National, the Woodwardian, the Oxford, and other Museums, 



