178 Prof. T. II. Jones on (he 



few montlis of his ileatli*, are at hand for reference and com- 

 parison. Not a few of these have been incorporated in the 

 accompanying Phites. 



The Ostracoda that still remain in the above-mentioned 

 Collections to be described are chiefly those appertaining to 

 Macrocyprisy Fontoci/pris, Bythocypris, Cythere^ Cytherella, 

 TIdipsura, /Echinina^ Pn'mitia, &c. ; and in estimating the 

 Jeading characteristics of the carapace, the relative size of the 

 two valves, the shape of each extremity, and other features 

 of the carapace, Dr. HoU's comparative drawings, often 

 several for one object, are vivid exj)ressions of his views on 

 the subject, and frequently of much service in determining 

 the genus and species, 



I. Macrocyphis, G. S. Brady, 1867. 



Cy there, Bairdia, &c., nuctorum. 



1867. Macrocypris, G. S. Brady, Intellectual Observer, vol. xii. p. 119 ; 

 " MonogT. iJeeent Brit. Ostrac.,' Trans. Liun. Soc. vol. xxvi. 1868, 

 p. 391 ; Report Ostrac. 'Challenger' Exped. 1880, p. 40. 



Carapace subcylindrical or long triangular, and often 

 Bairdia-\\kQj generally elongate, attenuated at the extremi- 

 ties ; valves thin, smooth, unequal, with bevelled plates 

 Avithin the ends, more or less sinuate on the ventral margin, 

 the right larger than the left and overlapping dorsally ; 

 hinge-line flexuous. 



This genus is a member of the section of the Ostracoda 

 known as PODOCOPA, and belongs to the family Cypridida?, 

 which comprises marine as well as freshwater species. 



Some specimens obtained from the Silurian shales appear to 

 belong to this genus, and represent certainly three undescribed 

 species. Formerly such specimens were referred to Gythere 

 a name used to cover tlie generic alliance of those small 

 Ostracoda M'hich could not be exactly or satisfactorily de- 

 termined. Now, however, that not only Gythere but its 

 allied genera have been fully elucidated in the living state, it 

 is found that the genus does not comprehend many of the 

 fossil forms once referred to it f- Whether these really 



* In September last. See Geol. Mag. for Nov. 18tt6, p. .527. 



t Dr. G. S. Brady's researches on the Recent Ostracoda have given 

 lis much clearer views than we had heretofore of the relationship of 

 these Bivalved Entomostraca, and have enabled us to refer several uf the 

 fost^il forms to their probable genera as represented among their modern 

 and existing allies. See, for instance, the paper on " Some Carbonife- 

 rous Ostracoda," Ann. & Mag. Nat. Hist, for October 1886. Among 

 Dr. Brady's many valuable memoirs and monographs we note more espe- 

 cially his '• jNlouograpli of the Recent British Ostracoda,"' Trans. Ijinn. 



