352 Prof. T. R. Jones and Dr. H. B. HoU on the 



This is referred to above (page 348). B. Kloedeni^ var. 

 graniiJata (some big-lobed), passing into var. tuherculatay 

 Salter, together with var. antiquata, have been found in 

 Upper-Silurian shales near Muirkirk and Lesmahago, 

 Lanarkshire. 



II. Lobes less free, attenuated. 



(4) Beyricliia Klosdeni^ var. intermedia^ Jones. 

 (PL XII. figs. 3 and 4.) 



Proportions : — Fig. 3 {subspissa) : L. 21. H. 14. Th. 10. 

 Fig. 4: L. 14. H. 8. 



This variety was distinguished and figured in the paper on 

 " Palfeozoic Bivalved Entomostraca " in the Proc. Geol. 

 Assoc. 1869, pp. 12 and 14, fig. 9._ 



Valves suboblong or nearly semicircular, with raised mar- 

 ginal rim and three nearly equal lobes, relatively narrow and 

 vertical, the middle lobe not being short-oval, but reaching 

 down into the ventral region and coalescing freely with the 

 lower ends of the other two lobes. An approximation to 

 this feature is evident in some specimens collected by Mr. 

 Smith from " Woolhope " and by Mr. Vine from the " Tick- 

 wood Beds " and tlie " Shales over the Wenlock Limestone." 

 In the latter, however, the lobes are somewhat thicker than 

 in the specimens from the Upper-Ludlow shales. 



In Mr, Vine's examples the surface is punctate or slightly 

 reticulate, but usually roughened. No two have exactly the 

 same outline and contours of lobes and margins. Some are 

 more semicircular than others, and some have the lobes 

 thicker and with less interspaces than others (fig. 3 a, h). 

 This last modification might be termed subvariety subspissa. 

 A raised marginal rim is distinct in all. This form is near to 

 and corresponds with the North-American B. lata (Vanuxem, 

 Ann. & Mag. Nat. Hist. ser. 2, vol. xvi. p. 168, pi. vi. 

 fig. 13). ^ 



Var. intermedia presents a more complete union of the 

 posterior and the central lobe in a horseshoe-shaped ridge 

 than is found in the typical form of B. Klcedeni, and herein 

 resembles B. Buchiana. The front lobe also is connected 

 Avith the middle lobe by a depressed neck, a condition observ- 

 able in B. Buchiana and some others. Besides the greater 

 distinctness of the lobes in B. Buchiana, the notching or ten- 

 dency to subdivision in its posterior lobe separates it from the 

 variety of B. Kladeai under notice, which was designated as 



