404 Prof. T. 11. Jones on the 



pits, wliich Fr. Schmidt describes as perforating tlie valve ; 

 here, however, they appear to be only shallow pits. 

 From the lowest limestone beds of CEsterffarn. 



VII. Thlipsura, Jones & Holl, 1869. 

 (Ann. & Mag. Nat. Hist. ser. 4, vol. iii. p. 213.) 



1. Thlipsura v-sc7-ipta, J. & H., var. discreta, Jones. 

 (PI. XXIl. figs. 9 a, 9 &, 9 c, 10.) 



Thlipsura v-scripta, J. ifc H., var. discreta, Jones, Silur. Ostrac. Goth- 

 land, 1887, p. 6. 



This species was described and its British variety figured 

 in 1869 by Jones & Holl (Ann. & Mag. Nat. Hist. ser. 4, 

 vol. iii. p. 214, pi. XV. fig. 3). See also op. cit. ser. 5, 

 vol. xix. p. 403. 



In the Swedish variety, of which about fifty specimens 

 form part of the series sent to me in 1886, the front sulcus is 

 oblique, being not quite perpendicular, and those on the 

 hinder half of the valve keep slightly apart, not closing 

 together to form the letter V completely. There is also a slight, 

 curved, convex ridge within and parallel to the posterior 

 margin ; but it is not always well developed. Dr. Krause 

 has figured this variety as Primitia minuta (Zeitschr. deutsch. 

 geol. Ges. vol. xxix. p. 38, pi. i. fig. 19). Abundant in the 

 shale of Frojel, 



VIII. Peimitia, Jones & Holl, 1865. 

 (Ann. & Mag. Nat. Hist. ser. 3, vol. xvi. p. 415.) 



1. Frimitia Icevis^ Jones. (PI. XXII. figs. 12 «, \2h.) 



Primitia Iwvis (parte), Jones, Silur. Ostrac. Gothland, 1887, p. 4. 



This is a smooth, subtriangular, somewhat Leperditioid 

 form, straight on the back, rounded at the ends, but one of 

 them much higher (broader) than the other. It appears to 

 be new. The only group to which I can refer it is that of 

 the smooth Primitice, such as P. matutina, semicircularis^ 

 ohsoleta, ovaia, and ohlonga^ in pi. xiii. Ann. & Mag. Nat. 

 Hist. ser. 3, vol. xvi. p. 423 &c. It is convex mainly in the 

 postero-ventral region. Its contact-edges are bevelled in- 

 wards, except along the straight edge, which seems to be the 

 back and hinge-line. It would more closely resemble P. ohso- 

 leta, J. & H., if it were shorter and less compressed anteriorly. 

 Edge-view (fig. 12^) narrow-ovate. 



