26 THE ENTOMOSTRACA OF 



Valves narrow, convex, smooth, occasionally punctate and spiny. Anterior extremity 

 obliquely rounded ; posterior subacute. Left (large) valve rather more elliptical on 

 the back than the right valve, its dorsal edge very slightly inverted ; the middle of the 

 ventral margin inverted. Hinge-margin of the rigid valve finely crenulated, and traversed 

 l)y a slight longitudinal furrow. 



Dorsal aspect compressed oval ; anterior oval. 



This species is abundant in the Charing Detritus, and occurs sparingly in the 

 Chalk, Gault, and Speeton Clay.^ A very similar form occurs in a greyish stratum of 

 Carboniferous Limestone at East Kilbride,' near Glasgow. This form also occurs 

 recent at the mouth of the Thames ; and a finely hirsute variety Mr. Williamson has 

 obtained from the Philippines ; all of which we are strongly disposed to consider 

 identical (as far as the carapace can bear evidence) with the species above described. 



This species is named in compliment to Mr. Harris of Charing, to whose long- 

 continued exertions and researches (commenced in 1839) we are indebted for a large 

 proportion of the series of Entomostraca at present under notice. 



No. 4. Bairdia angusta, Miinster. Tab. VI, fig. 18, a—f. 



Cythebe angusta, Miinster. 1830. Jahrbuch f. Min. p. 63, n. 10. 



CvTHERiNA L^viGATA, Roimer. 1840. Verstein. Kreid. p. 105, n. 5, pi. 10, fig. 20. 



— ATTENUATA, Reuss. 1845. Verstein. Bohm. Kreid. p. 104, n. b, pi. sxiv, fig. 15a, b. 



Length, -j-V 



Gault, Folkstone. 



Tertiary, Osnabriick {Miinster). 



Height, ^V 



Detritus, Charing. 



— Paris {Miinster). 



Thickness, Jy 



Chalk, Gravesend. 



— Bordeaux {Miinster). 



■ — CasteUarquato (Miinster). 



— Coralline Crag, Sutton.^ 



Chalk, North Germany {Roemer). Recent, Adriatic {Miinster). 



— Weinbohla, Saxony. — Arran, North Britain. 



Chalk-marl, Bohemia (BeifM). — Mouth of Thames. 



Carapace subovate, mytiloid, vaiiable in height and thickness. Valves narrow, 

 convex, smooth and glistening ; elliptical on the dorsal edge, more or less incurved on 

 the ventral border. Anterior extremity somewhat depressed, rounded ; posterior 

 narrow, gibbous, acute. The hinge-margin of the left valve is occupied by two smooth 

 bars, placed end to end, forming two arcs to the elliptical margin, and meeting at its 



1 This is the only species we have been enabled to obtain from the Speeton Clay. Our exammation of 

 this deposit has not been extensive ; the Microzoa, however, that it afforded, especially the Foraminifera, 

 were identical with those of the Gault. 



- Among some fossil microscopic shells, presented by Dr. Ure, of East Kilbride, to the Hunterian 

 Museum, Royal Coll. Surg. London, and referred to in his ' History of Rutherglen,' &c., p. 312, are some 

 fine specimens of a species apparently identical with B. Harrisiana. 



3 In Mr. S. Wood's Collection. 



