﻿COCCOSTEJD.fi* 



283 



1844. Coccosteus cuspidatus, L. Agassiz, ibid. pp. 28, 137, pi. xxxi. 



fig-. 4. [Median dorsal plate ; Edinburgh Museum.] 

 1848. Coccostens microspondylu*, F. M'Coy, Ann. Mag. Nat. Hist. [2] 



vol. ii. p. 298. [Imperfect skeleton ; Woodwardian Museum.] 

 1848. Coccosteus pusillus, F. M'Coy, ibid. p. 298. [Ditto.] 

 1848. Coccosteus ? triyonasjns, F. M'Coy, ibid. p. 299. [Ditto.] 

 1855. Coccosteus latus, F. M'Coy, Brit. Palseoz. Foss. p. (302. 

 1855. Coccosteus oblonyus, F. M'Coy, ibid. p. 603. 

 1855. Coccosteus microspondylus, F. M'Coy, ibid. p. 602, pi. ii. c. fig. 4. 

 1855. Coccosteus pusillus, F. M'Coy, ibid. p. 603, pi. ii. c. fig. 5. 

 1855. Coccosteus ? triyonaspis, F. M'Coy, ibid. p. 603, pi. ii. c. fig. 6. 

 1860. Coccosteus decipiens, Sir P. Egerton, Quart. Journ. Geql. Soc. 



vol. xvi. p. 128. 

 1860. Coccosteus milleri, Sir P. Egerton, ibid. p. 135, woodc. figs. 5, 6. 



[Edinburgh Museum.] 

 1875. Coccosteus decipiens, W. H. Baily, Figs. Charact. Brit. Foss. 



pl. xxxiii. fig. 3. 

 1880. Brachydeirus milleri, A. von Koenen, Zeitschr. deutsch. geol. 



Ges. vol. xxxii. p. 675. 

 1883. Brachydeirus milleri, A. von Koenen, Abh. phys. CI. k. Ges. 



Wiss. Gottingen, vol. xxx. p. 20. 

 1883. Brachydeirus pusillus, A. von Koenen, ibid. p. 20. 



1888. Coccosteus decipiens, II. H. Traquair, Geol. Mag. [3] vol. v. 

 p. 511. 



1889. Coccosteus decipiens, R. H. Traquair, ibid. vol. vi. p. 4, pl. i. fig. 2. 



Type. Imperfect skeletons ; British Museum. 



The type species, attaining a maximum length of about 0*4. 

 Cranial shield hexagonal in form, the outer lateral angles acute, 

 and the breadth between the latter considerably greater than the 

 total length ; median occipital much broader than long, abruptly 

 truncated in front, its anterior end being only half as broad as the 

 posterior ; the anterior two- thirds of the shield gradually arched 

 from side to side, flattened or depressed above, and the posterior 

 portion of the median occipital plate rising to a sharply bent longi- 

 tudinal ridge, corresponding to the laterally-arched contour of the 

 median dorsal plate of the trunk immediately behind. Median 

 dorsal plate as long as the cranial shield, and twice as long as 

 broad, much arched from side to side, gradually tapering in its 

 posterior half and produced into a long, blunt point ; anterior 

 border slightly excavated. Anterior ventro-lateral plates not much 

 longer than broad, shorter than the posterior ventrolaterals, which 

 are twice as long as broad and produced at each postero-lateral 

 angle into a short spine ; exposed portion of both median ventral 

 plates longer than broad, the lateral angulation of the posterior 

 median being almost at its middle point. Tuberculations of mode- 

 rate size, never confluent, and rarely, except in the lateral plates, 



