66 On the Palivozoic Bivahcd Entomostraca. 



9. Drepanella serotinn, Sandbcvger, MS., sp. n. 

 (PI. Yll. tig. 12.) 



Lenpfth. IIei<rht. 



iiiiliiin. millim. 



•76 -46 



For an account of the genus Drepanella see Ulricli's 

 memoirs (Journ. Cincinn. Soc, N. H. vol. xiii. 1890, p. 117, 

 and Geol. Surv. Miimes., Last Report, vol. iii. 1894, p. 670). 

 The present form may look upon D. ampla, Ulrich (1890, 

 ]). 120, pi. viii. tig. 2), as a near ally, although the sickle- 

 shaped ridge on the ventral region is shortened to a straight 

 thick ridge, and the two pointed knobs above are represented 

 by two unequal roundish tubercles. Hence the species is 

 ditferent for the German form ; and von Sandberger's name 

 serotina may well be adopted for this late^ if not last^ represen- 

 tative of the genus. 



Drepanella seems to have been an outcome of Bollia rather 

 than of Beyrichia ; but its evolution is not a matter for dis- 

 cussion at present. 



From the Lower Devonian of OfFdiUen, Dillenburg, Nassau. 



10. Strepula? annulotn, Sandberger, MS , sp. n. 

 (PI. Yll. fig. 13.) 



This very curious little unique form was found on a large 

 block of the OrtkocerasSchieier (Lower Devonian) at OfF- 

 diUen ; and fig. 13 is copied from the drawing supplied by 

 Prof. von. Sandberger. The outer ridges and central eleva- 

 tions are not quite comparable with the features of any known 

 Strejiula, but to that genus the present example seems to have 

 the nearest affinity. 



EXPLANATION OF PLATE VII. 



[The figures 1-7 are magnified 20 diameters, excepting figs. 4 c and 5 b, 

 which are xOO. Figs. 8-13 x30 diam.] 



Fif/. 1. Priviitia nitida (F. Roemer). a, left valve ; l 



6, edge view. ( 



Fi;i. 2. The same, an older individual, a, left valve ; " ^"6"^^, liarz. 



b, edge view. ) 



Fif/. 3. Pvimitia Icem^ata, sp. n. a, left valve ; b, edge ) 



view. [ 



Fif/. 4. Aparchiies reticulata, sp. n. a, right Aalve ; f ''^"^^"'^• 



i, edge view ; c, portion of ornament. ] 



