22 BRITISH PALJilOZOIC PHYLLOCARIDA. 



4. Ceeatiocauis tyrannus, Salter, MS., 1878. PL III, figs. 2, 3, 5, G, 8; PI. IV, 



fig. 4 ; PI. V, fig. 4 ; PI. IX, fig. 4 (?). 



1878. Ceeatiocaris TYBJLHtivs, Salter, MS., H. N. & E. Catal. Cambr. and Silur. 



Foss., M. P. G., p. 118. 



1884. — MuECHisoNi, La Toitche. Handbook Geol. Shropshire, p. 37, 



pi. 17, fig. 565. 



1885. — sTiOiA (part), T. E. J. ^if. JF. Tliird Eeport, Brit. Assoc, 



p. 345 ; Geol. Mag., 



1885, p. 396. 



1886. — ATJ'ENUATA, — Fourth Rep., Brit. As.soc, 



p. 230; Geol. Mag., 



1886, pp. 456, 457. 



Some abdominal segments (Oxford Mus. E ; Ludlow Mus. L ; B. M. 39403 ; 

 M. P. G. If and f f ), narrow in proportion to those in one other specimen marked, 

 ff, and referred to G. Murchisoni (above, p. 17), and very much narrower and 

 smaller than in G. gigas, we separated in 1 886 as belonging to a new species 

 called G. atteniiata, but we find that it is the G. tyrannus of Salter. They have 

 straight styles and stylets, much shorter than in either of the foregoing. 



Carapace not known, unless PL III, fig. 8, showing a fragment occurring on 

 the tablet marked f f , belongs to it ; if so, it is longitudinally striate. Segments 

 narrow, ornamented with longitudinal wrinkles, which curve up and down at the 

 anterior edge. Epimeral borders strongly defined and bearing joint-marks, either 

 for contiguous segments or for abdominal appendages (uropods). The ultimate 

 segment cylindrical (like others), straight-wrinkled, long, and narrow. Caudal 

 appendages straight, sharp, and rather short ; ridged and furrowed ; style pitted 

 (PL V, fig. 4). 



In a small specimen (PL III, fig. G) the stylet is 20 mm. long. ; and the style 

 was probably twice as long. 



(PL II, fig. 4, and PL V, fig. 6, have caudal appendages very similar to those 

 in PL III, figs. 3, 5, 6, and PL V, fig. 4, and possibly should be referred to G. 

 tyrannus rather than to G. Halliana ; but, taken together with PL IV, figs. 5 and 

 6, their carapaces graduate to that in PL II, fig. 1.) 



PL III, fig. 2. Some segments, and part of appendages, lying at right-angles, 

 and broken. Three body-segments shown as hollow casts. A tubercle on the lower 

 part of the anterior third of each segment is shown by an impression in the casts. 

 Longitudinal, wavy, irregular striae (impressions of wrinklets) mark the segments ; 

 curving and anastomosing at the anterior or proximal edge. Parts of three 

 caudal spines are present. Mus. Pract. Geol. Marked " ff. Lower Ludlow ; 

 Church Hill, Leintwardine. Geratiocaris tyrannus, Salter." See ' Catal. Camb. 

 and Sil. Foss., M. P. G.,' 1878, p. 118. In olive-grey mudstone; slightly micaceous. 



