4 
KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 23. N:o |2. 17 
By the table given above it is seen, that most of the seventeen species have 
been found in the uppermost stratum of Gotland, as it contains no less than 15 different 
species, of which all, a doubtful variety of A. cochleatum included, occur only in that 
stratum. Those, which occur in the lowest stratum, belong to a peculiar group. From 
the intermediate strata c—g there have as yet no specimens of Ascoceras, nor of the other 
genera been found, only in d some indeterminable fragments in the oolite of Bursvik and 
the limestone of Östergarn. In three species the Nautiloid has been found in connexion 
with the Ascoceras and in one, ÅA. fistula, both in the same stratum, but disconnected. 
There has no doubt once existed still more specific forms of Ascoceras in the strata of 
Gotland: -So may the shell figured in Pl. IV fig. 25 belong to a distinct species and 
also the specimen of the same plate f. 38—39, but we must abide till there is more 
material for a description. 
If an attempt were to be made to subdivide the species of Ascoceras in smaller 
groups, this will be possible only in a few instances and chiefly in consequence of their 
interior structure. 
Group 1 embraces the three species A. cochleatum, A. dolium and A. fistula. 
They are distinguished from the others in having the least number of sigmoid septa of all, 
viz. constantly three, but in compensation they alone have a regular septum between the sep- 
tum of the truncature and the first sigmoid, thus two regular septa, while all the others 
have only one regular septum, that which forms the bottom. In a certain way they resemble 
the species of Billingsites Hvyartt, having only three sigmoid septa and beneath these at 
least one of the ordinary shape. The two first are also ovoid, but their aperture is simple. 
Group 2 consists of the curious species A. decipiens, A. sipho and A. gradatum, which 
have the first element of the siphuncle constricted in its midst, as if it were to be divided 
into two. This duplicature exactly resembles the interior edges of the second normal septum 
in the preceding group. It is, as it were, the only traces of a second normal septum, 
which was only begun, and never completed or, perhaps rather, the only rest left of a 
septum which once existed. 
Shortly to repeat the history of this remarkable genus it seems to have been al- 
together unnoticed before BARRANDE in 1846 was the first to create it, giving it the name 
of Cryptoceras") in his »Notice préliminaire sur le Systéme Silurien et les Trilobites de 
Bohéme» p. 43. He there only says, that it is a »genre que nous avons créé pour classer 
des formes auparavant inconnues et trés-bisarres». Already in the next year”) he was 
obliged to change the name into Ascoceras, as the former was so nearly alike to Crypto- 
1) In 1849 DOrBIGNY (Cours élémentaire de Paléontologie et de Géologie I, p. 286) created a Cephalo- 
podan genus Cryptoceras apparently without being aware of BARRANDE'S older genus. That of D'ORBIGNY consists 
of two Nautiloid shells from the Devonian and the Carboniferous Formations. To increase the confusion the 
editor of the Second Edition of Woopwarp's Manual of Shells p. 189 included Ascoceras of BARRANDE us a Syno- 
nym within the Cryptoceras of D'OrRBIGNY. But in the Supplement there is a description of Ascoceras as BARRANDE 
left it, without any mention af its identity with Cryptoceras. 
?) In the second meeting, Sept. 1847, of the »Freunde der Naturwissenschaften in Wien», but the paper 
was not published before 1848 in HAIDINGER'S »Berichte iber die Mittheilungen von Freunden der Naturwissen- 
schaften in Wien» Bd. III, p. 268. —- Also in N. Jahrbuch fir Min. Geol. 1848, p. 764. 
K. Sv. Vet. Akad. Handl. Band. 23. N:o 12. 3 
