COCCOSTEID^l. 
309 
1860. Heterostius eurynotus , E. von Eichwald, Letli. Rossica, vol. i. 
p. 1524. 
Type. Fragment of dermal armour. 
The type species, of very large size, known only from separately- 
discovered bones. Eorwardly-directed process of anterior dorso¬ 
lateral more than twice as long as the remainder of the bone. 
Ornamentation sparse. 
Form, Loc. Lower Devonian: Livonia. 
The following are plaster casts of the original bones from Livonia 
in the University of Dorpat, described by Asmuss, and were pre¬ 
sented by Sir Roderick I. Murchison, K.C.B., abuut 1846 :— 
15142 j. Imperfect median dorsal plate, shown from the inner 
aspect and the posterior margin placed uppermost by 
Agassiz (op. cit. pi. xxxii. fig. 13); the type specimen of 
H. TiuecJcii , Asmuss (op. cit. p. 28, no. 1), described as 
“ scutum dorsale anterius.” 
15142 k. Fragment of middle portion of a similar plate (Agassiz, 
pi. xxxii. fig. 8); the type specimen of H. grcicilior, 
Asmuss (p. 28, no. 2). 
151421. Anterior portion of inner keel of median dorsal shield; 
the type specimen of H. convexus , Asmuss (p. 28, no. 3). 
15142 m. Fragment of median dorsal shield (Agassiz, pi. xxxii. 
figs. 11, 12); the type specimen of H. eurynotus , Asmuss 
(p. 28, no. 4). 
15142 n. Imperfect right anterior dorso-lateral (Agassiz, pi. xxxii. 
fig. 19); described by Asmuss (p. 30, no. 19) as “ admi- 
niculum laterale ” of H. eurynotus. 
15142 0. Similar bone, less imperfect, but scarcely more than half 
as large as the latter (Agassiz, pi. xxxii. fig. 18, Pander, 
pi. viii. fig. 1"); described by Asmuss (p. 30, no. 18) as 
H. convexus. 
15142p. Fragment of process of similar bone; assigned to H. in¬ 
gens by Asmuss (p. 30, no. 20). 
15142 q.. Expanded portion of -a similar bone, left side ; the type 
specimen of H. secunclarius , Asmuss (p. 30, no. 22). 
15142 r. Similar specimen, showing overlapping fragments poste¬ 
riorly ; the type specimen of H. initialis, Asmuss (p. 31, 
no. 25). 
