Palceozoic Bivalved Entomostraca. 405 



This may be provisionally known as P. Icevis. Though 

 the smooth Primitue. pass by gradation into the sulcate forms, 

 possibly a subgeneric term might be usefully applied to them. 



So far as its outline is concerned P, Icevis much resembles 

 Leperditia tyraica, Fr. Schmidt ; but its internal edges are 

 not those of Leperditia^ nor has it the special surface-charac- 

 ters of that genus. 



Only two specimens (from the shale of Frojel) were among 

 those sent in 1886. 



2. Primitia stricta^ sp. nov. 

 (PI. XXII. figs. 13 a, 13 b.) 



P)-imitia Icevis (parte), Jones, Silur. Ostrac. Gothland, 1887, p. 4. 



More compressed than fig. 12, and with less height at the 

 posterior third, this unique specimen is more oblong in outline, 

 with parallel sides. Edge view (fig. 13 h) narrow oblong, 

 but acute in front and rounded behind. From Frojel, in 1886. 



In shape this approximates to Primitia variolata^ J. & H. 

 (Ann. & Mag. Nat. Hist. ser. 3, vol. xvi. p. 418, pi. xiii. 

 fig. 6) ; but it is not so evenly rounded at the ends and has 

 neither the sulcus nor the punctation. It is smooth, like the 

 little P. matutina^ J. & H. [he. cit. fig. 7), but differs from it 

 in shape. 



3. Primitia valida, J. & H. 



Primitia valida, J. & H., Ann. & Mag. Nat. Hist. ser. 5, vol.xvii. 1886, 

 p. 409, pi. xiv. fig. 7, and vol. xix. p. 193, pi. vi. fig. 7 ; Silur, Ostrac. 

 Gothland, 1887, p. 4. 



In the Swedish specimens (of which twenty-four were sent 

 in 1886) the reticulation of the surface is much more definite 

 than in the British examples. There is also a distinct row 

 of minute denticles along the ventral edge of each valve in 

 many of the Swedish specimens. 



From Frojel. 



4. Primitia grandis, Jones. 

 (PI. XXII. figs. 14 a, 14 6, 14 c.) 



Primitia grandis, Jones, Silur, Ostrac. Gothland, 1887, p. 4. 



One of the drawings sent from Stockholm shows a beauti- 

 ful, large, suboblong, reticulate Primitia without a sulcus. It 

 is near P. valida, J. & H., and, indeed, in one of the varieties 

 of that species the sulcus is obsolete, namely var. breviata [ojj. 



Ann. & Mag. N. Hist. Ser. 6. Vol. i. 28 



