42 THE ENTOMOSTRACA OF 



Generally the English specimens slightly differ from M. Bosquet's figures in almost 

 wholly wanting the longitudinal parallel furrows on the ventral surface, which are 

 continued transversely and concentrically 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 specimens. One such 

 transverse furrow, immediately posterior to the lucid spots, near the centre of the 

 valve, is nearly always present, even in young specimens. I have not met with 

 individuals retaining the setse of the surface. 



Cy there {Cytheridea) Mulleri occurs throughout the Tertiary formations of Europe ; 

 being found in Austria, Bohemia, Hesse, Westphalia, France, Belgium, and the 

 Netherlands, in the Eocene; in Touraine {Miocene); and in the Netherlands 

 {Pliocene). In England it occurs abundantly in many of the shales of the 

 Hempstead series, at Hempstead Cliff, Isle of Wight ; and one specimen was met 

 with in a green shale of the Osborne series, at Cliff End, Isle of Wight ; it is not rare 

 (as the var. intermedia) in the Barton Clay of Hampshire ; and the clay with oysters 

 from Colwell Bay, Isle of Wight, yielded three or four specimens ; these deposits are 

 of the Upper Eocene group : and in the Woolwich and Reading series (Lower 

 Eocene) it has been found at Clay Hill, 1 near Newbury, Berks, and is abundant at 

 Woolwich, Kent. This species also occurs in a tertiary blue clay, given to me as 

 having been brought from Australia ; and I have a small recent specimen from the 

 Australian seas. M. Bosquet also records this species as living in the Zuyderzee, 

 Holland. 



M. Reuss has figured under the name of Cytherina intermedia a form which he 

 derived from the Barton Clay of Hampshire : this is evidently identical with the 

 unfurrowed variety (pi. 5, fig. 4) from the same deposit. M. Reuss regards it as 

 intermediate between C. Mulleri, Minister, and C. seminulum, Reuss {loc. cit., p. 59, 

 t. 9, figs. 5 — 8), which latter in all its varieties appears to me to belong to Von 

 Miinster's species. 



Var. torosa, Jones. Plate VI, fig. 12. 



Cythere (Cytheridea) Mulleri, var. torosa, Jones. Quart. Journ. Geol. Soc.,x, p. 161, 

 t. 3, fig. 8 ; and Memoirs Geol. Survey, 1856", p. 158, t. 7, fig. 27. 



INCH. 



Length, y 1 ^ Upper Eocene : Hempstead Cliff. 



Lower Eocene : Woolwich. 



This variety differs from the typical C. Mulleri in being generally smaller (although 

 sometimes as long, though not so nigh as the type), and in having the surface of the 



1 In the sandy clay-beds with Ostrcea Beltovacma. 



