28 BRITISH PALAEOZOIC PHYLLOCAEIDA. 



venience, however, we have kept together those having carapaces ; especially as 

 these appear to graduate in shape from the very small specimens PI. IV, figs. 5 

 and 6, to the large one PI. II, fig. 1. 



PI. II, fig. 1. Carapace showing the left valve. This large carapace is imper- 

 fectly preserved, but shows all its shape, except that the anterior angle has been 

 broken off. The valves are very thin; a portion of the left valve is present; and 

 the right valve is represented in part by an impression of its outside ; and its 

 remainder is covered by the compressed layer of matrix which lies between the 

 two valves, and the broken edge of which is exposed along the middle of the 

 specimen. The valves were apparently quite smooth, and are slightly crumpled 

 by pressure ; the portion preserved is traversed by fine cracks, along and athwart, 

 causing it to break into more or less quadrangular pieces. 



Mus. Pract. Geol., marked "x^. Lower Ludlow; Church Hill, Leintwardine. 

 Ceratiocaris leptodactylus, M'Coy." See ' Catal. Cambr. and Silur. Fossils, M. P. G.,' 

 1878, p. 142. In olive-grey mudstone,' weathering brownish. 



PI. II, fig. 2. Carapace, five or six abdominal segments, and part of the caudal 

 appendages. Right valve shown, smooth, glazy, very thin, crumpled into irregular 

 longitudinal folds, and breaking into small angular pieces. The posterior edge 

 has been misshapen by pressure on the internal body-segments. The exposed 

 segments are much crushed, but six are recognisable ; the four above the 

 penultimate retain their lower edges (though broken) ; and traces of a longitudinal 

 striation are present here and there in all. The attachment of the style (telson) 

 is obscure ; also the individuality of the style and stylets. The presence of the 

 teeth is indicated by minute mamillary projections in the anterior third of the 

 valve. The front angle of the valve has been damaged. In the matrix beyond it 

 is an irregular row of little pits, which seem to be the casts of small, short, hollow, 

 ring-like bodies, possibly the remnants of some part (antenna?) of the animal 

 protruded from the valves ; or they may be some bodies altogether distinct. 



Mus. Pract. Geol., marked " x y. Lower Ludlow ; Leintwardine. Ceratiocaris 

 lejptodadylus, M'Coy. Presented by A. Marston." See ' Catal. Cambr. and Sil. 

 Foss.,' 1878, p. 142. In olive-grey, micaceous mudstone, weathering brown. 

 Some casts of small Rhynchonella-like Brachiopods He in the matrix. 



This may be the specimen referred to by Mr. Salter in the ' Ann. Mag. Nat. 

 Hist.,' March, 1860, p. 158. 



PI. II, fig. 3. Carapace and four or five segments. This specimen is chiefly 

 an impression, but with some films of the test, showing a right valve, smooth 

 (glazy), but wrinkled by pressure along the ventral margin. The maxillge are indi- 

 cated by their mark within the valves. Five abdominal segments, much crushed, 



1 Some of the mudstone, containing the specimen of Ceratiocaris from Ludlow, is calcareous, 

 especially in very thin seams at the edges of the slabs. 



