DITHYROCARIS TESTUDINEA. 151 



ventral faces ou the shale, and these appear to have been sulcate, with granula- 

 tions (possibly adventitious) on the median ridge. The dorsal faces have only a 

 small portion of the top end of each preserved, showing a median ridge, and 

 otherwise sulcate. 



This may belong to a small variety or a young form of the normal D. testwlinea. 



It is comparable in size with the trifid of Geratiocaris minuta of our ' Mono- 

 graph Brit. PalfBOZ. Phyll.,' 1888, p. 47, pi. x, fig. 11, and pi. xi, fig. 10. 



In black shale, non-calcareons. East Kilbride. Paton Coll. 



PI. XXIII, fig. 8. Brit. Mus. 59541, Xo. 29. 



Size. — Penultimate segment 3 mm. long in its most perfect part. Ultimate 

 segment 6 mm. long ; style obscure ; stylets 13 mm. long. 



Characters. — The penultimate segment is marked with transverse wavy lines 

 and the ultimate with oblique lines; thus comparable with D. testudinea. 



In this small tail-piece the three spines have been pressed together, and one of 

 them (the style) is quite obscured as to character and i-elative size. The two 

 largest spines are cercopods (stylets) of equal length, and are sulcate. 



This little specimen, in dark-grey calcareous shale, was collected by the late 

 Dr. Rankin in Lanarkshire. 



PI. XXVII, figs. 3 rt, h. Neilson Coll., H. 

 Size. — Length about 34 mm. ; width about 2 mm. 



Characters. — A small, delicate specimen of an isolated dorsal crest like that 

 attached to the valve shown in PI. XXVIII, fig. 1. 



In black shale, slightly calcareous. Kirktonholm, East Kilbride. 



PL XXVIII, figs. 1 a, h. Neilson Coll., D. 



Size. — Length, including the spine, about 85 mm. ; width about 37 mm. 



Characters. — The right-hand moiety (magnified) of a good carapace of D. 

 testudinea, having besides its usual characteristics a well-max'ked cristate dorsal 

 ridge, which is absent in all the specimens hitherto described. A separate 

 example, however, of such a dorsal ridge is also preserved in Mr. Neilson's cabinet 

 (PL XXVII, fig. 3). 



Black shale, non-calcareous. East Kilbride. 



PL XXVIII, fig. 2. Neilson Coll., C. 



Size. — Width at the top of the piece about 35 mm. ; width between the points 

 of the two spines 24 mm. ; width between the bases of the two spines 20 mm. 



Characters. — The posterior portion of a well-preserved right-hand moiety or 

 valve of D. testudinea, showing the exact form of the hinder edge and the two 

 posterior spines. 



Black calcareous shale. East Kilbride. 



