58 BRITISH PALEOZOIC PHYLLOCARIDA. 



26. CfiRATiocAitis cassia, Salter, 1860. PI. VII, figs. 7 a, 7 b, 7 c, 7 d, 7 e. 



I860. Ceratiocaris cassia, Salter. Ann. Mag. Nat. Hist., ser. 3, vol. v, p. 159. 



1865. — — Huxley & Etheridge. Catal. Fossils M. P. C, p. 79. 



1867. — — Salter. In Siluria, 3rd (4th) edit., p. 516. 



1877. — — H. Woodward. Catal. Brit. Foss. Crust., p. 70. 



1878. — - H., N. & E. Catal. Camb. Sil. Foss. M. P. Gh, p. 141. 



1885. — — T. R.J.& H. W. Third Eeport Pal. Phyll., p. 348 ; 



Geol. Mag., 1885, p. 463. 



1886. — — — Fourth Eeport, p. 231 ; Geol. 



Mag., 1886, p. 458. 



C. cassia is recognised on an interesting slab, of which one counterpart is 

 in the Ludlow Museum (E and F) and the other in the Museum of Practical 

 Geology at Jermyn Street, London (x y). Neither gives the form quite complete ; 

 the lower specimen on each slab seems to have been much modified. They are the 

 originals seen and noticed by Mr. Salter. 



The carapace is suboblong, horizontally striate ; truncate, with an ogee outline 

 behind ; pointed in front ; postero-dorsal angle above the median line ; anterior 

 angle on the median line ; 20 mm. long, and 11 mm. high. Of the body-segments 

 one or two are exposed, altogether 6 mm. in length, longitudinally or obliquely 

 striate. Telson and stylets rather short, sharp, delicately ridged ; stylet 4 mm., 

 style about 9 mm. long. 



Figs. 7 a, 7 b, Ludlow Museum E and F ; figs. 7 c, 7 d, 7 e, M. P. G. x T . 

 From Lower-Ludlow beds, at a roadside quarry, Trippleton Farm, near Leint- 

 wardine. Marked " Ceratiocaris cassia, Salter." Both counterparts consist 

 of a greenish-grey, rather hard mudstone, fine-grained, slightly micaceous, and 

 somewhat calcareous, especially along thin whitish seams at the edge. 



Two carapaces are represented by two pairs of thin brown valves, much 

 squeezed and crumpled. The upper carapace retains its ogee hinder border, and its 

 pointed front extremity, both much above the medial line, but on the long axis 

 of the valves. Marginal rim strong ; the surface is ornamented with delicate, 

 longitudinal, and parallel strias. The lower carapace is more distorted than the 

 other, blunter in front, and squeezed into a narrower shape. 



Besides the wrinklings by pressure, there are irregularities of the surface due 

 to internal organs in the anterior moiety of each carapace. In the larger (upper) 

 carapace there is a minute, flask-shaped, pitted depression just beneath a very 

 small pimple in the anterior region. At first sight these marks have the look 

 of ocular tubercles ; but after careful examination we are not inclined to give them 

 that importance. 



