CERATI0CAH1S TYRANNUS. 23 



PI. Ill, fig. 3. Four segments and crushed fragment of telson and a stylet, 

 preserved as hollow casts, with traces of joints at the epimeral borders, as above. 

 Mus. Pract. Geol. Marked " § f . Geratiocaris tyrannus, Salter. Leintwardine." 

 In olive-grey mudstone. See ' Catal.,' 1878, p. 118. 



PI. Ill, fig. 5. A small specimen of five body-segments, and caudal appendages 

 crushed. There is a tubercle (joint-mark) in the lower front of the penultimate 

 segment and the next above, and fainter in the other two. There is also a half- 

 round joint in the posterior angle (indistinct) of the penultimate segment. The 

 ultimate segment has straight striae. There are also faint indications of a rounded 

 posterior angle, and of an acetabulum on the telson, crushed up ; that is, 

 there is an obscure joint-like hollow on it to fit against the lower posterior' angle 

 of the ultimate segment. The telson-head has a minute leaf-like anastomosing 

 ornamentation, not shown in fig. 5. Mus. Pract. Geol. Marked " f f . Wyatt- 

 Edgell Collection. Lower Ludlow, Leintwardine. Geratiocaris tyrannus, Salter." 

 See ' Catal. Camb. and Sil. Foss.,' 1878, p. 118. 



PL III, fig. 6. Four segments and appendages imperfect. The rounded head 

 of telson is rather more distinct than in the figure ; but no corresponding articular 

 facet is left at the angle of the ultimate segment. Head of the stylet is appa- 

 rently rounded, and more distinctly pressed into the lower angle of the ultimate 

 segment than in the figure. Indication of a joint-socket at the lower posterior angle 

 of penultimate segment (not in figure). Telson and stylet ridged longitudinally. 

 The ultimate and penultimate segments show the inside of their tests. The next 

 is a hollow cast of the outside of the shell ; and the uppermost segment shows its 

 outside. 



B. M. 39403. Greenish-grey micaceous mudstone with impressions of Biscina 

 and other small shells (not Brachiopods), and impressions of fossil plant and 

 Orthoceras ? Lower Ludlow ; Ludlow. A. Marston Coll. 



PI. Ill, fig. 8. This is part of a carapace- valve, longitudinally striate. Stria? 

 very fine on the dorsal region, coarser along the middle, and coarsest along the 

 ventral region. (On the back of this specimen is the smooth convex cast of a small 

 right valve, 1 as small as Oxford Mus. J., PI. IV, fig. 6, and with truncate posterior 

 like that of Oxford Mus. K., fig. 5) Mus. Pract. Geol. Marked " f f. G. tyrannus, 

 Salter. Leintwardine." See ' Catal.,' 1878, p. 118. 



In brownish-grey micaceous mudstone, like other pieces of the same §§. 



PI. IV, fig. 4. Seven segments (convex casts with films of the test), broken- 

 in along their upper thirds, and part of the other side shown by impressions above 

 and beyond them. Tubercle (? joint) with hollow upper face, strong on the 

 penultimate and the next segment, and faint on that preceding. Terminal portions 

 of two of the caudal spines are present. The ultimate segment is pinched-up along 

 1 An oblique fragment of shell imitates a tail in this little specimen. 



