186 BRITISH PALAEOZOIC PHYLLOCARIDA. 



This specimen is embedded in a bard black shale of the Cement-stone, 

 micaceous and calcareous, containing obscure small Ostracods. It is associated 

 with three other pieces of the same shale, including its counterpart ; m 4269 b 

 shows another, but imperfect trifid; m 4270 h contains the fragment of a small 

 dorsal rugose ridge. This is 15 mm. long, and represents probably two-thirds of 

 the original, and is evidently the relic of some small or immature carapace, only 

 about 20 mm. in length. 



13. Dithyrocaris Dunnii, sp. nov., /. and W. Plate XXIII, figs. 9 and 10; 



PI. XXIX, figs. 1 and 2. 



PI. XXIII, figs. 9 and 10. Dunn Coll., *& and ^. (Redesdale.) 



/-Style 10 mm. long; 6 mm. broad at top (head or caudal 

 Size.— Fig. 9 {*£■) \ plate). Ventral ? aspect. 



v. Stylets broken (fragments 11 mm. long). 

 r Style 10 mm. Jong ; 5 mm. broad at top (head or caudal 

 „ Fig. 10 ( ^f) \ plate). Dorsal aspect. 



^Stylets broken (fragments 8 mm. long). 

 Specific Characters. — The two specimens (figs. 9 and 10) serve as the type of 

 the species. They were collected by Mr. John Dunn, of Redesdale, from the 

 "deaf" nodules in the Redesdale shales. 1 A part of the last abdominal segment, 

 much crushed, is retained in each specimen, smooth, with a broad, flat, trifid tail 

 attached. They are peculiar on account of the broadly triangular style and the 

 narrow stylets, originally rather longer than the style, and obscurely silicate. 



PI. XXIX, fig. J. Mus. Geol. Surv. Scot!., F f, No. 16. (Larriston Burn.) 

 fig. 2. Mus. Geol. Surv. Scotl., F *£ No. 19. (Harelow Hill 

 Quarry.) 

 Q . „. ( Style imperfect, 20 mm. long; 7 mm. wide at the top. 



I Stylet (the most perfect) 30 mm. long. 



/•Style imperfect, 30 mm. long (not much longer originally); 10 

 ,, Fig. 2 < mm. wide at the top. 

 ^ Stylets broken. 

 Characters. — These two imperfect specimens, though much larger, seem to be 

 closely related to D. Dunnii (PI. XXIII, figs. 8 and 9), by the relatively short and 



1 See page 176. The ironstone nodules in the uppermost bed of shale are called "deaf" when 

 they have become oxidised. 



