240 
XAUTTLOIDKA. 
1 
^2^. Char. “ Shell much compressed laterally, flattened upon the 
periphery ; the latter broad, with (in the cast) rounded borders. 
The greatest width of the whorls is in the umbilical region. The 
umbilicus is ver}* small. The septa are moderately distant, the 
sutures very strongly bent, first forward in a narrow lobe on leaving 
the umbilicus, then backward in a broader one, then sweeping for- 
ward again and making a conspicuous sinus on the periphery. The 
siphuncle is situated considerably above the centre. 
Remarks. “ Though Oppel, Zittel, and Neumayr unite in regarding 
Nautilus Strainhercfensis as a distinct species from the present one, 
the resemblance between the two is very striking. The only differ- 
ence between them is in the form of the sutures, which make 
a wider (backwardly directed) lobe on the sides of the shell in 
N. Franconicus than they do in N. Stramberr/ensis, and this dis- 
tinction is expressed in the figures of the latter given by Zittel 
(loc. cit.), which otherwise agree perfectly Avith specimens of 
N. Franconicus with which we have compared them. The name 
Franconicus was originally conferred by Oppel ^ upon a specimen 
from the Lithographic Slate of Solenhofen. 
The locality of the specimen figured is unknown, but it agrees in 
all essential points wuth the German specimens in the Collection, 
and adds to our knowledge of the species the characters of the body- 
chamber and of the test. The latter is smooth, being ornamented 
only with delicate lines of growth. The last two septa are exposed 
by the removal of the test. A strong ridge is developed near the 
base of the body-chamber, its indented outline corresponding roughly 
with that of the last suture. Part of the anterior boundary of the 
shell-muscle is seen on the cast of the body-chamber (see fig. 57 a). 
The aperture is deeply emarginate. 
“In an excellent figure of this species given by v. Ammon (loc. cit.) 
the anterior border of the shell-muscle is represented upon the cast 
of the body-chamber.” {Foord and G. C. Cnck.) 
Horizon. Tithonian. 
Localities. Normandy, EscragnoUes (Yar), France ; Randen, near 
Schaffhausen, Switzerland ; Einsingen, Wiirtemberg. 
^ “ Die Tithonische Etage ” (Zeitschr, der Deutsch. geol. Gesell. Band xvii.), 
p. 54G. The “ Tithonian ” is a special group of the Upper (White) Jura, 
including the period embraced between the Oxfordian and Portlandian series. 
See Oppel’s ‘Die Juraformation Englands, Frankreichs und des siidwestlichen 
Deutscblands,’ 1858 ; also Zittel, “ Die Cephalopoden der Stramberger Scbichten,” 
Palaeont. Mittheil. Band i. Abth. ii. 1868. 
J 
