Notes on Species of Ceratiocaris. 391 



tbe back ; outlined by a bold elliptical curve on the ventral margin, 

 whicb rises up to form with the dorsal edge a sharp angle in front, 

 above the median line of the valve ; but this and other features 

 were varied by age and sex, and have been modified by pressure 

 in the different specimens. The antero-ventral margin is sometimes 

 indrawn, making the point in front more acute. The hinder margin 

 is truncate with an elegani; ogee curve, full below, and ending 

 above in the postero-dorsal angle, often but not always sharply 

 defined. In some cases the ventral margin is much deeper than in 

 others. Some fragments of carapaces from Leintwardine (Ludl. 

 Mus. 0., and M. P. G. f f ) are ornamented with longitudinal lines 

 or striee of varying strength. 



Seven abdominal segments are usually exposed. 



Good specimens of C. MurcMsoni (Agass.) : — 



M. P. G. X i. — Carapace, 125 x 55 mm., with acute prow. Smooth, longitudinal 



linear ornament. Long form of carapace. Leintwardine. 

 M. P. G. X y.— Carapace, 60 x 28 mm. Smooth and glazy. 



Seven segments, about 50 mm. (the last one about 20 mm.). 

 Telson crushed. Long form of carapace. Leintwardine. 

 Ludl. Mus. D. — Carapace, 50 x 30 mm. Smooth. 



Seven segments, 55 mm. (the last one 20 mm.). Some with 



straight strise. 

 Telson imperfect. Short form of carapace. Leintwardine ? 

 Ludl. Mus. B. — Carapace, about 50 x 30 mm. Short form of carapace. 



Exposed segments (crushed up), 50 mm. With straight, wriggly- 

 striae. 

 Telson broken. Leintwardine. 

 M. P. G. x^. — Carapace, 40 x 20 mm., with acute prow. Smooth and glazy ; 

 at the place of the teeth. 

 Five ? segments, about 30 mm. Long form of carapace. Leint- 

 wardine. 

 M. P. G. X J .—Carapace, 25 x 1 1 mm. Small, smooth, sharp in front, marked 

 by teeth inside. 

 Seven ? segments, 28 mm. (the last one 14 mm. ). Linear ornament. 

 Telson, 25 mm. Ridged and pitted (spines). (Stylets about 

 12 mm. Ridged.) Long form of carapace. The whole animal 

 3i inches in length. Bow Bridge, near Ludlow. 

 Ludl. Mus. A. — Carapace, 24 x 13 mm. Small, smooth, subovate, sharp in front. 

 Seven segments, 30 mm. (the last one 12 mm.). Longitudinally 



striate. 

 Telson imperfect (12 mm. preserved). Medium form of carapace. 

 Leintwardine ? 

 Oxford Mus. J, K, Q, are small specimens from the Lower Ludlow, with features 

 closely resembling those of C. Murchisotii. 



Addendum. 

 1853. Dithyrocaris Murchisoni (Agass.), Geinitz. Verstein. Grauwackenformation 



in Sachsen, u.s.w. Heft 2, p. 24, pi. 19, fig. 13. 

 1866. Ceratiocaris Muixhisoni, Jones. Ann. Mag. N. H. ser. 3, vol. xviii. p. 40. 



This is the distal end of tapering, costulate telson (or stylet ?), and 

 is quite comparable with C. Murchisoni (Agasfeiz), as indicated by 

 Dr. H. B. Geinitz. It was obtained from the Silurian Grauwacke 

 beds of the Gunzenberg, between Moschwitz and Pohl, near Plauen, 

 together with Graptolites, Orthoceras, and Fterinea. 



