546 
PERIPETOCERAS FRIESLEBENI, Geinitz (Leonh. et Bronn, /ahré., 
1840001. xi, igs yrs Figs: 1=3; Pl. xi. 
Loc., Tunstall Hill, England, Dyas. : 
This shell has a metanepionic substage with a subangular abdo- 
men and siphuncle propiodorsan. The umbilical perforation is 
small and a dorsal furrow appears in the paranepionic substage. 
The apex, as shown in Fig. 1, Pl. xi, is narrow and compressed ; 
the metanepionic, Figs. 2 and 3, broadens on the dorsum but 
remains rounded; the dorsal furrow at its first appearance, just 
beyond the gyroceran bend in the paranepionic, is deeper, as shown 
in Fig. 3, than it is subsequently when opposite the largest diam- 
eter of the umbilical perforation, Fig. 2, and the whorl changes at 
the same time from digonal to trapezoidal or temnocheilan-like. 
The siphuncle, however, remains propiodorsan. 
The neanic substage has a nephritic outline and in the ephebic 
stage the volution becomes subquadrate with a flattened abdomen. 
The living chamber is somewhat over one-fourth of a volution in 
length, with broad, shallow, hyponomic sinus, broad, low, lateral 
crests and sinuses on the umbilical zones. 
The siphuncle continues to be propiodorsan in position. 
The sutures have broad, ventral and dorsal lobes and lateral 
lobes. There are annular lobes in older stages according to 
Geinitz. I could find none in the early ephebic stage of the single 
specimen from Tunstall Hill, which showed a perfect septum, but 
they may be present in later substages. 
Syringoceras,* n. g. 
This genus has been framed for Triassic species like the type, 
Syringoceras granulosostriatus, which have a tubular, nepionic volu- 
tion with the siphuncle subventran. The early nepionic shell is 
also ornamented with very closely set transverse ridges, but it has 
no longitudinal ridges until a comparatively late stage. This nepi- 
onic ornamentation is like that of the genus Hercoceras at the same 
age. The impressed zone is present only after contact and is not deep. 
The genus includes the group of Vautidus Barrandet of Mojsiso- 
vics, the equivalent of Mawtilus linearis, Laube, and SS. (Vaut.) 
evolutum, sp. Mojsisovics. 
Syringoceras (Waut.) granulosostriatus and linearis, stated by 
* Sooty, a tube. 
