250 



mitted for our examination by Mr. E. A. Walford, F.G.S. 

 They are figured in the fifth plate issued herewith. 



One piece of the Bradford Clay from Bradford (Geol. Mag., 

 1886, p. 273) has yielded a few specimens which are also 

 treated of here. 



A bibliographic list of works treating of the Jurassic Ostracoda 

 (omitting those of the Lias and the Purbeck beds) is given in the 

 Quart. Jourii. Geol. Soc, vol. xl., p. 776. To this list may be 

 added the paper on the species obtained from the boring at 

 Tiichmond, Surrey, described in the same volume, and M. O. 

 Terquem's memoir on the Ostracodes from the Inferior Oolite* 

 t)f the Department of the Moselle, in France (M6m. Soc. GM., 

 France, s6r. 3, vol. iv., 1885). The latter is elaborate and fully 

 illustrated ; but we are not satisfied with all the generic deter- 

 minations, and the drawings in some instances leave much to 

 be desired. Another such memoir by M. Terquem treats of the 

 Ostracoda of the Inferior Oolite near Warsaw, 1886. 



The figures on the five plates illustrating this present memoir 

 give the valves with the anterior extremities upwards ; the 

 dorsal and ventral margins being on the right and left hand, 

 as the case may be. Of course, this position is not in accordance 

 with the natural habit of the animal when swimming ; but it is 

 a convenient arrangement in plates, and often adopted. Hence 

 the height of the valves (from the ventral to the dorsal margin) is 

 occasionally referred to in the text as the (apparent) breadth. 



In every case the specimen has been mounted on a "Beck's 

 revolving disc," and drawn under the camera; and thus the several 

 views that we have given of each individual type of a species 

 have an assured correctness. 



The Ostracodous Genera mentioned in our note in the Geological 

 'Magazine, June, 1886, have been more accurately determined in 



* One figure, p. 100, pi. xviii., fig. 1, seems to approach our C. 

 pentagonalis, p. 261. 



