300 
ARTHRODIRA. 
By E. von Eichwald {tom. cit. p. 1529, pi. lvii. figs. 4, 5), the 
originals of Pander’s pi. vii. figs. 3, 9, 15, are assigned to C. ver- 
neuili; while those of the latter author’s pi. vii. figs. 3 b , b', 11,12, 
14, with an indeterminable fragment named “ plaque dentaire,” are 
regarded as the types of a distinct species, C.posthumus. The so- 
called C. griffithii, M‘Coy (Ann. Mag. Nat. Hist. [2] vol. ii. 1848, 
p. 8), from the Lower Carboniferous of Cultra, Co. Down, Ireland, 
is a generically indeterminable jaw (C. H. Pander, cit. p. 87). 
[Dublin Museum.] 
/*7V. - ^ s .. > r ' 7 4 . A c 
, Genus DINICHTHYS, Newberry, ' - 7 ^^ ' 
Ltd'Ll fritz ■ asT.C7^.y^\ ■ Zs /’S+O- *r , 
^ P * ^ Eep * GeoL Surv - 0hi ° 7 To1 * i - P 1 * iL 1873 > P- 313 «] a!Sv^/’ 
Head and trunk broad, the dorsal aspect slightly arched from side 
p s'p to side; scutes smooth or feebly marked with vermiculating rug®; 
! ^caudal region destitute of armour. Elements of cranial shield almost 
^ or completely fused in the adult, and the occipital bones constituting 
' **' ^? ss r ^ an °f its total length; a distinct small median bone over 
V the pineal region, with a minute perforation; orbits forming broad 
notches, not bounded externally : eye with a ring of few sclerotic 
plates ; maxilla distinct, and two inner pairs of dentigerous bones in 
the upper jaw ; mandibular rami suturally united at the symphysis, 
each beak-shaped in front, and bearing a short, single series of 
V• 
Eig. 45. 
A. 
B. 
Diagrams of dentition of Linichthys, after Newberry.—A, anterior, and B, 
lateral aspect of jaws of D. terrelli; C, anterior aspect of jaws of 
D. hertzeri. 
a 
a 
acute teeth anchylosed just in advance of the middle of its oral 
margin. A single median dorsal shield upon the trunk, with an 
inner longitudinal keel, and rounded or acutely pointed posteriorly ; 
ventral armour of trunk well developed, consisting of two large 
lateral plates and a long narrow median element equivalent to the 
two diamond-shaped median bones of Coccosteus fused together ; 
ventral and dorsal armour united by lateral plates, of which the 
anterior dorso-lateral exhibits a large articulating eminence, but has 
i/cA. \ | Jhrfj . r? 
