82 



BRITISH FOSSILS. 



and breastplates of a mediseval warrior, and is divisible into two 

 portions, the dorso-lateral and the ventral shields — the former com- 

 posed of nine pieces, the latter of six. Of the nine pieces of the 

 dorso-lateral shield, seven are closely articulated together, while the 

 other two, small and comparatively insignificant, (and not represented 

 in the dorsal view, fig. 19) were placed loosely at the sides of the 

 posterior end of the great median plate of the seven. This plate a 

 corresponds in width, anteriorly, with the cranial bone S.O. ; 

 it widens a little behind the middle of its length, and then rapidty 

 tapers to a point. From the middle of its under surface it sends 

 down a strong bony crest, deeper behind than in front, while its 

 lateral edges overlap and unite, by a squamous suture, with the 

 plates S.s. and h. 



S.s. is a four-sided plate, articulated with Pa. Ep. in the manner 

 before mentioned, while behind it overlaps the triangular plate h, 

 and below is overlapped by the plate c. The latter is so constantly 

 thrown out of its place in specimens where the connexion between 

 a, b and S.s. is perfectly retained, that I suspect it rather over- 

 lapped than was suturally united with S.s. 



The ventral shield appears to me to have had no direct connexion 

 with the dorsal. I have examined a large number of specimens 

 with reference to this point, but I have never discovered the lc;ist 

 evidence of a sutural union between any two elements of the two 

 shields, though the respective constituents of each shield are con- 

 stantly met with in all stages of union and disunion. Of the 

 elements of the ventral shield, two are median and symmetrical, 

 four lateral and in pairs. The two latter, upon each side, are broad 

 at their remote ends and narrower at their adjacent ends, whose 

 outer edges are, besides, somewhat bent up. Of the median plates, 

 the posterior is rhomboidal and articulates with all the others ; the 

 anterior has the form of an elongated isosceles triangle, whose 

 base, directed anteriorly, is rounded off and forms the middle of the 

 anterior margin of the ventral shield. 



The stout, doubly curved, clavicle-like bones Mn., found, in com- 

 plete specimens, on the under side of the head, have one edge beset 

 with minute denticles for a short distance ; and there are two other 

 flat, elongated, bones, devoid of sculpture upon their outer surfaces, 

 which lie between them and the anterior edge of the ventral 

 shield. 



Beside the parts now described, the only other bones known to 

 belong to Coccosteus are the neural and subcaudal arches, the fin- 

 rays and their supports, and the curved ossicles which lie just 



