^'AU^ILID^. 
i i 
Bemarks. Barraude draws attention to the resemblance between 
Hercoceras minim and JSautilus siihtubercidatus, G. & F. Sandberger 
(Die Yerstein. Nassau, 1856, p. 133, pi. xii. f. 3), in the general 
form of the shell, the slightly embracing whorls, ornaments of the 
test, &c. A complete comparison between the two forms cannot, 
however, be made, as the aperture in N. subtiiberculatus is wanting. 
It may be mentioned that Dr. E*. Kayser' places some examples 
of the last-named species from the Hartz in Barrande’s genus 
hercoceras, but with some doubt, remarking that the Ithenish 
and Hartz form corresponds in all observed characters with Herco- 
ceras minim, and if the ai^ertaro should prove to be similar the 
analogy between the two species would be complete. My own 
opinion is that the two forms — Hercoceras minim and Nautilus 
subtiiberculatus — are sj)ecijicallti distinct (the enormous develop- 
ment of the spines in the former being quite sufficient to separate it 
from the latter), but as to whether they belong to the same genus 
or not can only be determined by the discovery of more perfect 
specimens of N. subtiiberculatus. 
Horizon. Etage G, bande g 3 ( = Downtonian). 
Localitij. Hlubocep, Bohemia. 
AVeU represented in the Collection. 
Genus BARRANDCOCERAS, Hyatt'. 
{Uraiioceras, Hyatt ^.) 
(Jen. Char. Shell discoid, compressed, rather widely uuibilicated, 
exposing all the volutions, with a large central perforation ; increas- 
ing rather rapidly in diameter. Section sublanceolate, the concave 
wider than the convex side. Septa deeply concave, rather distant; 
the sutures forming a shallow sinus upon the sides of the shell and 
upon the periphery. Surface of the test transversely costate, or 
provided merely with lines of growth. 
Type, Nautilus natator, Billings h 
Ordovician to Silurian. 
Remark's. With Barrandeoceras may be associated Cyrtoceras 
Uraniim, Barrando {=Uranoceras Uranum, Hyatt), of the Silurian 
1 ‘ Die Fauna der altesten Devon-Ablagerungen,’ in Abhandl. zur geol. 
Specialkarte v. Preussen, 1878, Band ii. Heft iv. p. 86. 
^ Proc. Boston Soc. Nat. Hist. 1883, vol. xxii. p. 209. 
3 Ibid. p. 298. 
* Canadian Naturalist and Geologist, 1859, vol. iv. p. 466. N. natator not 
having been figured, I have given a figure of A". Buhemicum, Barr. 
