170 
PROF. D. M. S. WATSON AND MB. E. L. GILL ON THE 
articulated with it on a downward curve, and would Le subjected to much 
greater strains during the maceration undergone by the skull before its burial. 
The nasals are shown in their natural position in several skulls in the Ro5'al 
Scottish Museum ; one skull from Newsham, in the same museum (No. 
1S78.45.7), shows several prenasal ossicles in position as well. They are 
introduced in fig. 1, p. 164. In the Atthey Collection there are a number of 
detached nasals and prenasals. Both are much more variable in shape than 
the other bones of the skull-roof behind them (see fig. 3, p. 167). All the 
prenasal ossicles seem to be crossed on the underside by a ridge and 
groove (fig. 3, F, G, H, J, p. 167), which may mark the position of a lateral- 
line canal. 
Fig. 6. 
Sagenodus. OutlinBS of specimens, showing marginal ossicles and circumorbitals. 
A. Fi'om the Virtuewell Seam, Newarthill, Lanarkshire. Royal Scot. Mus. (1897/110/31). 
pt.r. &, pt.L, right and left pterygoids with their teeth t.r. & t.l. ; man., mandible. 
B. Prom the same horizon and locality as fig. A. R.S.M. (1897/112/5). 
C. Coal Measures, Liuton, Ohio, U.S.A. British Museum (N.H.) (P. 7773). 
Circumorhitals and Marr/inal Ossicles. 
These bones frequently occur scattered among the other bones in dis- 
articulated examples of Sagenodus on slabs of shale, and in the Atthey 
Collection there are large numbers of them in this sort of association or as 
isolated bones freed from the matrix. Many of them were certainly orbitals, 
for they have one of their edges thinned out and rounded, and leading on the 
