8 A. SMlTFt WOODWAUD, U. 1)EV0NIAN FlSH-REMAlNS. 



of the dorsal part of tlie carapace. The speciraen is pre- 

 served as far forwards as the inwardly directed laminar 

 Slipport (a) for the base of the lateral appendage, which is 

 broken away. All the other borders ■ seein to ])e complete. 

 The upper and lower borders are nearly parallel or slightly 

 convergent backwards. The hinder börder is bent, so that 

 it ends in a l)lnntly-ronnded point about its middle (2>), jnst 

 above the notch and groove for the sensory canal (s). The 

 postero-inferior angle is obscnred by matrix in the specimen 

 fignred, bnt is well shown in a niore imperfect example of 

 the plate in the same block of sandstone. The inner lamina 

 of the bone displa^^s only the concentric lines of gro^Yth, and 

 the scattered pittings due to nutritive canals in cross-section. 

 The onter face, where exposed, is seen to l)e covered with a 

 coarse ornament of low, ovate and ronnded tnT)ercdes like 

 those of the anterior median dorsal. The surfaces of overlap 

 are not very easily determined, T)nt they seem to be qnite 

 normal. A cross-section of the plate at its anterior end, 

 displayed by the concave side of the fossil, seems to prove 

 that the upper börder was overlapped. The external orna- 

 ment reaches to the lowermost edge of the plate as preserved, 

 Imt there may have been an overlapped margin beyond. The 

 manner in which the fossil has split near its hinder börder 

 evidently indicates that the straight line marked o is the 

 abrupt termination of the thickest part of the plate behind, 

 the triangulär area beyond this being thinner to overlap the 

 posterior dorso-lateral element. 



Part of a left anterior ventro-lateral plate (no. 4) is 

 also readily identifiable, and agrees with the element just 

 described in indicating a short and deep trunk. This spe- 

 cimen is incomplete anteriorly and displayed from the in- 

 ner aspect (fig. 13). Its imperfect counterpart on another 

 slab (no. 4, a) is associated apparently with part of a se- 

 cond plate of the same kind; while other specimens of 

 the right side also occur in the collection (nos. 1, 1 rt, 

 1 b). The ventral lamina of this plate is nearly flat, 

 apparently only rising in front to the thickening for the 

 support of the appendage, where it is broken awa3^ The 

 ascending lamina (1) rises almost at right-angles: in the spe- 

 cimen fignred it is imperfect at each börder, hut the other 

 examples show that its depth at the anterior thickening is 



