310 
ARTHRODIRA. 
15142 S. Imperfect median occipital, shown from the inner aspect 
and the posterior margin placed uppermost by Agassiz 
(pi. xxxii. fig. 7), and figured by Pander {op. cit. pi. viii. 
fig. I 10 ) ; the type specimen of H. ingens , Asmuss (p. 29, 
no. 9), described as “ scutum dorsale posterius.” 
15142 t. Right lateral occipital (“ mastoid ” or marginal, Pander, 
pi. viii. fig. I 9 ), figured by Agassiz (pi. xxxii. figs. 15, 
16), the glenoid extremity being placed uppermost; 
described by Asmuss (p. 32, no. 16) as “ os multifixum ” 
of H. eurynotus. 
15142 U. Portion of similar bone; assigned by Asmuss (p. 32, 
no. 15) to H. gracilior. 
15142 V. Bone figured by Agassiz (pi. xxxii. fig. 17) and identified 
by Pander (pi. viii. fig. I 5 ) with the anterior extremity 
of the postorbital; described by Asmuss (p. 32, no. 38) 
as left “ os incunneatum ” of H. convexus. 
15142 w. Portion of bone identified by Pander (pi. viii. fig. I 5 ) 
with the hinder half of the postorbital; described by 
Asmuss (p. 32, no. 17) as upper half of left “ os inter- 
jectum.” 
The right half of a median dorsal plate of Heterosteus, from 
Dorpat, is described by S. Kutorga 1 as the coracoid of a genus of 
reptiles, Ichthyosauroides, allied to Ichthyosaurus. This is regarded 
as the type of a distinct species of Heterosteus, H. Jcutorgce, by 
Asmuss {op. cit. p. 29), and the original of the first of the under¬ 
mentioned plaster casts is also assigned to it. 
15142 x. Hinder middle portion of small median occipital (“ scutum 
dorsale posterius,” Asmuss, p. 29, no. 8), probably refer¬ 
able to young individual of H. ctsmussi; original from 
Dorpat. 
Presented by /Sir Roderick I. Murchison , K.C.B., about 1846. 
15142 y. Portion of left half of a similar bone, assigned to H. con¬ 
vexus by Asmuss (p. 29, no. 10); original from Dorpat. 
Presented by Sir Roderick I. Murchison , K.C.B ., about 1846. 
Several bones found associated with those of Homosteus and He¬ 
terosteus in the Lower Devonian of Livonia are also represented in 
the Collection by plaster casts, presented by Sir Roderick I. Mur- 
1 Zweiter Beitr. Geogn. u. Palaont. Dorpat’s, 1837, p. 35, pis. v., v. 
