DITHYROCARIS NEILSONI. 187 



broadly triangular styles. Better specimens, however, are desirable for definite 

 determination. 



Fig. 1, from the dark-coloured calcareous shale of the Calciferous Sandstone 

 group at Larriston Burn, six miles north of New Castleton, has the head of the 

 style crushed, but obscurely striate as if masked with the dorsal face of an ultimate 

 segment, broken and displaced. The stylets are coarsely striated, one of them long 

 and curved, has 8 or 9 costula? ; the other has left only an impression of part of 

 its proximal end. Together with it is a portion of a strong oblique rugose ridge. 



Fig. 2, from the dark-coloured calcareous (?) shale of the Calciferous Sandstone 

 group at Harelow Hill Quarry, Pentou, Cannobie, has the head of the style pyri- 

 form, longitudinally striate, narrowing and sulcate below. There is an obscure 

 fragment of one stylet. 



14. DiTHYKOCABis Neilsoni, sp. uov., /. and W. Plate XXIX, figs. 3 a, 3 i, 



3 c. Neilson Coll., K. 



Size.—Yig.Sa^ 



C Style 22 mm. long (including the head). 

 Stylet 23 mm. long. 

 ,, Fig. 3i — Stylet 26 mm. long. 



( Style (broken) 18 mm. long; 3 mm. wide near the top. 

 " ^^" ^H Stylet 15 mm. long. 



Specific Characters : 



Fig. 3 a. — These are three slender caudal spines of nearly equal length, all 

 sulcated. Dorsal aspect. The style has a mid-ridge. The others ai-e not quite 

 perfect at the top. 



Fig. 3 h. — There is one stylet, slender, not quite perfect, slightly curved, and 

 sulcate; the other is lost. The style is bayonet-shaped. 



Fig. 3 c. — Caudal spines apparently sulcate ; dorsal aspect. 



All in black shale, some with adventitious granules. Small Molluscan shells 

 lie in the shale. 



Compare these with the trifid shown in PI. XXIII, fig. 7, which is of still 

 smaller size, but has the style longer than the stylet. 



From Bast Kilbride. 



15. Sp. PL XXI, fig. 10. Brit. Mus., No. 594541, No. 22. 



Characters and Size. — Caudal segments and appendages. Ventral aspect. The 

 ultimate segment, tapering from a breadth of about 12 mm. at top to 6 mm. below> 



