alceozoic Bivaloed Entomostraca. 65 



7. BeyricMa strict is ulcata, Sandberger. MS., sp. n. 

 (PL VII. fig. 11.) 



This oblong BeyricMa is allied to B. Kloedeni by its well- 

 developed three ridges, which, as in somewhat similar forms, 

 stand out nearly equal, equidistant, and almost parallel. It 

 is sufficiently distinct, however, to bear Prof, vou Sandberger's 

 proposed name of strictisulcata. 



It occurs, together with Atri/pa and Primitia sacculus, in 

 the dark grey, fine-grained sandstone at OfFdillen above men- 

 tioned, and is fairly abundant. 



8. Bollia varians, Sandberger, MS., sp. n. 

 (PL VII. figs. 8-10.) 



This characteristic Bollia is longer and more nearly oblong 

 than the majority of the published figures of this genus. The 

 form most closely allied is Bollia ungula (Claypole, MS.), 

 Jones, Amer. Geologist, December 1889, p. 338, tigs. 10-13. 

 The chief differences are : — (1) in the Nassau specimens here 

 figured the inner, semicircular, or horse-shoe ridge is not so 

 thick and is more open ; (2) the dorsal end of one half of the 

 horse-shoe forms a knob in figs. 8 and 10 ; (3) the second ridge 

 is larger and more distinct than in B. ungula^ though (as 

 in the Pennsylvanian examples here referred to) its ventral 

 portion is sometimes evanescent. 



B. unguloidea and suhcequataj Ulrich, and B. scmilanata^ 

 Jones, are shorter, rounder, and otherwise different ; so also 

 is B. Hindei, Jones, in which both tops of the horse-shoe 

 ridge are contracted to knobs ; and this is a feature with one 

 of the tops in both unguloidea and suhcequata. 



The specific characters of these German specimens (figs. 8- 

 10) are well marked, and the unstable features of the curved 

 ridges support Prof, von Sandberger's suggested name of 

 varians for this species, which is rather rare in the Lower 

 Devonian of Off'dilien, Dillenburg, Nassau. 



Ann. (& Mag. N. Hist. Ser. 6. Vol. xv 5 



