526 
on the third fragment. This shows that it did not begin to exist 
in this shell until late in the neanic stage and the younger nepionic 
stage must have been similar to that of Estonioceras. 
It is also interesting and suggestive to note that the depth and 
development of the dorsal lobe correlates exactly with the depth 
and breadth of the contact furrow. The lateral asymmetry in the 
dorsal lobes of the sutures is another fact to be noted in this speci- 
men. 
The central whorls existed in this specimen, but were completely 
concealed by the matrix. A section was made of these, but they 
exhibited no structures. 
The siphuncle was not visible. 
This cast reminds the observer more closely of Hstonzoceras (?) 
lamellosum, as figured by Angelin and Lindstrom, than any other 
form, but according to Schréder this last is a true estonioceran form 
- with only a slight contact furrow. 
Nedyceras. 
This genus was described by the author in Genera of Fossil 
Cephalopods, p. 281. It includes a large number of species with 
subtrigonal whorls, the dorsum much broader than the venter, 
which is elevated and usually subangular. The siphuncle is sub- 
ventran and quite large. 
The sutures have ventral saddles, lateral lobes and the dorsum 
may have a slight lobe or be nearly straight. The genus is of inter- 
est in this connection because, although completely coiled and the 
whorls in contact in several forms and although the whorl approxi- 
mates to the nephritic outline, it never has an impressed zone.: 
This is easily accounted for when one examines the figure of Vedy- 
ceras vestustum, Barrande, Pl. ‘‘ 35.’’ This shell shows that, 
although close-coiled, the rate of growth is slow and the umbilical 
perforation very large, so that there is no pressure of one whorl 
upon another. 
The genus has a number of forms in the Devonian, which also 
show similar peculiarities whether they are similar or more open in 
their coiling than vestustum, or have the turbinate mode of growth, 
which last is not unusual. 
The shells are all smooth. 
