158 BRITISH PALAEOZOIC PHYLLOCARIDA. 



PI. XXI, figs. 7 a, b. Mus. Geol. Surv. Scotl., m 4273 J , No. 16, and m 4274*, 



XX 



F -3- (bis), (counterparts). 



Dithtbocakis testudinexjs. B. JSiheridge, jun., 1879. Quart. Journ. Geol. Soc, 



vol. xxxv, p! 465, pi. xxiii, fig. 1. 



Size. — Length of the valve in fig. 7 b, imperfect, 30 mm. ; breadth of the 

 valve about 15 mm. 



Characters. — Two counterparts ; an embedded left valve (fig. 7 a), and its 

 cast (fig. 7 b). Both ends of the valve are imperfect. The mesolateral ridge is 

 rugose, and stands up sharp on fig. 7 a ; its hollow mould is seen in fig. 7 b. 



The fringed edge of the ventral margin extends as far as the fracture, narrow- 

 ing forwards ; as it is impressed on both of the counterparts, it must have stood 

 out free. The smooth ribbon-like band within the ventral margin is slightly 

 convex in fig. 7 b, and slightly hollow in fig. 7 a. 



These two casts of one moiety of a carapace were regarded by Mr. R. Ether- 

 idge, jun., as representing two separate valves. It was from its general shape 

 probably that Mr. Etheridge referred this specimen to Dithyrocaris testudinea; 

 but there are no remains of the peculiar ornaments of that species. Possibly it 

 may belong to D. Scouleri, M'Coy, which also had smooth valves (or moieties) ; 

 and in shape the hind part of the valve agrees sufficiently well. 



This left half of a carapace is embedded in a split piece of brown, semi- 

 bituminous, calcareous shale, which is micaceous, and largely composed of small, 

 obscure, compressed Ostracoda. 1 It is from the Cement-stone group of the 

 Calciferous Sandstone series, in the Tweeden Burn, near its junction with the 

 Liddel Water, by New Castleton, Roxburghshire. Posidonomyae occur also in this 

 specimen of shale. 



6. Dithyrocaris funiculata, sp. nov. Plate XXII, figs. 6 a — d. Mus. Geol. Surv. 



Scotland, F X T % No. 21. 



Size. — The fragment of a black filmy right valve 45 mm. long, probably 

 50 mm. or more when it was perfect. From the ventral margin to the meso- 

 lateral ridge 15 mm. ; the whole valve was probably 30 mm. wide. 



Specific Characters. — One of two displaced valves. A rather narrow moiety 

 with rather straight ventral edge. Anterior portion lost; the ventral margin 

 strongly marked with close-set oblique stria?, not forming a fringe, but a cord-like 

 pattern throughout (figs. 6 a and c) ; its posterior angle (fig. 6 b) shows a sub- 



1 Just as some of the oil-shales are constituted. 



