453 
mode of coiling, very variable aspects, owing to the closer coiling 
of some specimens than of others. 
There is no impressed zone in most specimens at any stage, 
although there is a slight flattening of the dorsal side and an 
obvious although very slight modification. of the dorsum, which 
takes place in the most closely coiled shells. 
The whorl in section is closely similar to that of afafor and the 
siphuncle similarly situated. The sutures are similar, with the 
exception of a faint dorsal lobe that appears in this species. 
The whorls do not touch in some specimens at all (Pl. xiv, Fig. 
2); in others they may touch in the neanic and ephebic stages. In 
some they may become excentric in the gerontic stage, and in 
others this may occur earlier in the ephebic stage. Very likely 
there is more than one species included under the name, but it is 
obvious that they are transitional to Barrandeoceras Sachert. 
BARRANDEOCERAS SACHERI. 
NAUTILUS SACHERI, Barrande (Sps¢. S77, Pl. xxxix). Pl.'v, Fig. 
II-T4. 
Loc., Bohemia. 
The large umbilical perforation is shown and the almost straight 
form of the ana- and metanepionic substages. The paranepionic 
substage has sutures with dorsal lobe (Fig. 13) and form with flat- 
tened dorsum (Fig. 14), precisely like that of the close-coiled forms 
of Sterndergi in the ephebic stage. In B. Sachert, however, the 
coiling is not variable and a contact furrow is invariably formed 
after contact, which takes place always as in Fig. 11, at the apex. 
The sutures in the ana- and metanepionic substages have ventral 
and dorsal saddles and form in section with similar position of 
siphuncle to Barrandeoceras natator of the Chazy and resemble 
Sternberg? only in the paranepionic substage. | In the neanic stage, 
after the impressed zone is generated, the whorls become more 
compressed and this resemblance is less noticeable. 
BARRANDEOCERAS TYRANNUM. 
NAUTILUS TYRANNUS, Barr. (Sys¢. S77, Pl. xxxvili). Pl. v, Fig. 6-10. 
Loc., Bohemia. 
This species is similar to Sacherz, but has a smaller umbilical per- 
foration and is somewhat closer coiled, the contact furrow appear- 
ing sooner and the Sternberg? stage of the paranepionic is consid- 
erably shortened. Its first appearance in the outline of the aperture 
is shown in Fig. 6 in the paranepionic substage. 
