18 
NAUTILOIDEA. 
prolonged in a larger curve beyond the rest, leaving in one example 
a space measuring 9 lines between the concave margin of the free 
portion and the convex margin of the coiled part. The diameter 
of the whorls increases about twice in each volution. The section 
appears to be nearly circular, the superior lateral angles being 
rounded b The septa are numerous, about 35 in a volution ; their 
distance apart increases very slowly, it is about i the shell-diameter. 
The siphuncle is placed at a distance of about i the shell-diameter 
from the convex margin, and is very slightly inflated between the 
septa. The surface is ornamented only with transverse lines of 
growth. 
Remarks. This species is readily distinguished from Trochoceras 
lamellosum by the greater distance of its septa, and l)y its less rapid 
rate of increase. 
Horizon. Ortlioceras-JAmes,ioYiQ ( = Arenig). 
Locality. Kinnekulle Hill (Westrogothia), Sweden. 
Kepresented in the Collection by a single imperfect example. 
Trochoceras speciosum, Barrande. 
1867. Trochoceras speciosuin, Barrande, Syst. Sil. de la Boheme, vol. ii. 
pt. i. p. 95, pi. xiv. if. 12-15. 
1882. Trochoceras speciosum^ Blake, British Foss. Ceph. pt. i. p. 219, 
pi. xxviii. f. 3, pi. xxix. ff. 1, 2. 
Sjp. Char. Shell discoid and flattened, although the internal 
whorl is slightly elevated helicoidaUy. The enrolment is dextral. 
The transverse section is oval, the two axes nearly as 6:5, the 
longest being the ventro-dorsal. The rate of increase of the last 
whorl is as 1 : 2. The body-chamber, which is not quite complete, 
occupies about ^ of the outer whorl. The form of the aperture is 
not known, but it probably agrees with that of the transverse 
section. The septa are very close together, about 15 may bo 
counted in the space of 1 inch, beginning at the base of the body- 
chamber ; they are but very slightly concave. The siphuncle is 
placed close to the convex border ; it is composed of short, rather 
thick segments, having an oval section. The segments are con- 
siderably contracted at the necks. The diameter of the siphuncle 
is about 1 the ventro-dorsal diameter of the shell. Only fragments 
of the test have been seen, they show no ornament. 
Remarks. Two of the specimens referred to this species show 
^ The section of this species has nerer been figured, and the specimen in the 
British Museum is too imperfect to afford any reliable information on this point . 
The shape of the section is therefore inferred from Hisinger’s figures. 
