PalcBOZoic Bivalved Entomostraca. 397 



A group of Silurian Macrocyiyrides, such as M. Vinei^ 

 might at first sight be thought to be comparable with such a 

 group of the Carboniferous Bairdia suhelongata as described 

 and figured in the Quart. Journ. Geol. Soc. vol. xxxv. 1879^ 

 p. 573, pi. XXX. figs. 1-11 and 16 (especially figs. 1 and 7) ; 

 but however near an approach they may seem to make, the 

 Macrocyprides have not the characteristic Bairdian outline of 

 the postero-dorsal border. They also have the right valve 

 larger than the left. 



II. PoNTOCYPEis, G. O. Sars, 1865. 

 (Ann. & Mag. Nat. Hist, ser. 5, vol. xix. 1887, p. ] 82.) 



1. Pontocrjpris Mawii, Jones. 

 (PI. XXII. figs. 3 a, 3 6, 3 c.) 



Pontocypris Mawii, Jones, loc. cit. pi. iv. figs. 4-6. 



A few examples with Bythocypris Hollii came from the 

 Frojel shale. The specimen here figured differs slightly from 

 the type in the convexity of the posterior third. The hinder 

 border in fig. 3 a is not specially depressed, but being somewhat 

 translucent shows the inner lamina. 



III. Bythocypris, G. S. Brady, 1880. 

 (Ann. & Mag. Nat. Hist. ser. 5, vol. xix. 1887, p. 184.) 



1. Bythocypris symmetrica^ Jones. 



Six specimens sent in 1886, showing slight modifications 

 of outline, agree sufficiently well with Bythocypris sym- 

 metrica, Jones {op. cit. p. 186, pi. vii. figs. 3 and 4), for them 

 to be referred to that species (Silur. Ostrac. Gothland, 1887, 

 p. 6). From Frojel. 



2. Bythocypris conciiuia, Jones. 



Bythocypris concinna, Jones, Ann. & Mag. Nat. Hist. ser. 5, vol. xix. 

 p. 186, pi. V. fig. 6 ; Silur. Ostrac. Gothland, 1887, p. 6. 



Judging from the drawings sent from Stockholm, this 

 species is represented in the Stockholm Collection. This is 

 one of the most widely spread species, found in the uppermost 

 strata of ffistergarn, Linde klint, and Hoburg ; and in the 

 shale of Stora Carlso. 



