JONES WOOLWICH ENTOMOSTRACA. 161 



figures in almost wholly wanting the longitudinal parallel furrows on 

 the ventral surface, which are continued transversely and concen- 

 trically across the anterior half of the valve ; faint traces only of the 

 concentric furrows being occasionally seen, though irregular transverse 

 furrows full of pittings are conspicuous in old specinaens. One such 

 transverse furrow, immediately posterior to the " lucid spots " near 

 the centre of the valve, is always present, even in young specimens. 

 I have not yet met vdth well-preserved individuals retaining the setae 

 of the surface. 



Varieties of Cytheridea Mulleri occur throughout the Tertiary 

 formations ; being found in Hesse, Austria, Bohemia, Westphalia, 

 France, Belgium, and the Netherlands, in the Eocene ; in Touraine 

 {Miocene) ; and in the Netherlands {Pliocene). M. Bosquet also 

 records this species as recent, — living in the Zuyderzee, Holland. In 

 England varieties of this species occur in the Coralline Crag, the 

 Barton Clay, and the tertiary sands of Coldwell Bay. 



2. Cytheridea Mulleri, Miinster, sp. ; var. torosa, Jones. 



Pl. III. fig. 8. 



The variety differs from the typical C. Mulleri in having the sur- 

 face of the valves raised up into 1-7 irregular lumps or bosses. Of 

 these knobs, which are often but ill-defined, sometimes seven can 

 be counted on one valve. The spots most usually occupied, when the 

 bosses are but few, are the posterior part of the valve and the cen- 

 tral part immediately in advance of the place of the " lucid spots." 



This variety has some resemblance to the C. trihullata, figured 

 and described by Dr. A. E. Reuss, Haidinger's Verhandlungen, 

 vol. iii. p. 60. pl. 9. fig. 10, one specimen of which (since lost) I 

 have found in the Barton Clay. In general form G. torosa resembles 

 that variety of C. Mulleri, in which the posterior extremity is con- 

 tracted and acuminate (var, acuminata. Bosquet ?) . 



Found plentifully together with the typical form in the above- 

 mentioned Woolwich deposits by Mr. Rosser. 



3. Cythere Wetherellii, Jones. Pl. III. fig. 9 a, 9 6. 



This elegant little species of Cythere proper has valves of an ovate 

 shape, contracted posteriorly, compressed on the ventral surface, and 

 with a somewhat triangular indentation at about the middle of the 

 dorsal part. The profile of either valve is almost a parallelogram. 

 The surface of the valves is ornamented by a delicate reticulation, the 

 meshes of which are formed by slightly raised anastomosing borders. 



I found several specimens of C. Wetherellii in clay with oyster- 

 shell fragments from Woolwich. 



The name borne by this new species is well knovra to the students 

 of Tertiary Geology. 



4. Cythere Kostelensis, Reuss, sp. Haidinger's Verhandlungen, 



vol. iii. p. Q>S. pl. 9. fig. 22. Pl. III. fig. 10. 



Two specimens of a minute oblong Cythere from amongst Mr. 



