KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 23. N:o |2. 13 
HraArTt'") disregarding the fundamental similarity in structure, placed his own ge- 
nus Billingsites amongst the Mesoceratidex and the other genera in the family of the 
Ascoceratide and both these families next each other between the Gomphoceratida and 
the Melonoceratide. There is no valid ground to separate Billingsites from the Ascocera- 
tide and join it with Mesoceras. This latter genus, which has been founded by BARRANDE 
on a single specimen — none having since his days been found — is known only by the 
living chamber, which highly resembles that of the Gomphoceratid:e, with which group 
also FISCHER and Foorp have united it. There 1s no evidence whatever of septa like those 
of Ascoceras and there is consequently no foundation of placing it with the Ascoceratidan 
genus Billingsites. 
HYATT also included Ophidioceras amongst the Ascoceratida because »the costated, 
compressed whorls have some resemblance to those of Ascoceras and the aperture is closely 
similar to Glossoceras». The exterior resemblance, as to the ornamentation, is very slight, 
if any, and the similarity of the aperture is of no signification when the most important 
character, the sigmoid septa, is wanting. The dispositions of Hyatt must then be chan- 
ged thus, that Billingsites is to be placed amongst the Ascoceratide near Glossoceras on 
account of its contracted aperture, while Ophidioceras may keep its more natural place 
amongst the Lituitidse, which has been given it by BARRANDE. bStrangely enough HYATT 
has revivified Aphragmites in spite of its disavowal by its own author BARRANDE. HYATT 
thinks »it is a distinet genus with simple septa and sutures». According to BARRANDE 
its chief characteristic should, however, consist in its total want of septa, which also is 
indicated by its name. 
MILLER joins Conoceras BRONN with Ascoceras. But if that genus, as is likely, is 
identical with Bathmoceras, there is no reason to retain it within the Ascoceratide. 
The question of the systematic place of the Ascoceratida has got a somewhat chan- 
ged aspect since the discovery of their earlier stages of growth. In this earlier shell there 
is nothing at all which might exclude them from the large group of the Nautiloidea. We 
find the same sort of septa and siphuncle in them all. Then it must be decided to which 
family or genus it bears the closest affinity. The gently curved shell, gradually tapering, 
the position of the siphuncele close in the vicinity of the ventral side, its perfect concor- 
dance as to the bulbous or nummuloid form of the elements in the Ascoceras and the 
strongly recurved necks of the septal apertures are features common to both the Ascocera- 
tide and a large group of numerous species of Cyrtoceras, those figured on plates 108—160 
of BARRANDE. Peculiar to the Ascoceratide is the feature that the septa are placed at 
irregular intervals and at the longest distance the more they approach the Ascoceras proper. 
Choanoceras is more deviating through the shape of its septa, which remain nearly the same 
during its growth, and through the central position of its siphuncle. Nevertheless it may be 
reckoned as am outlying member of this family through the conformity of its uppermost 
septa with those of the Ascoceras. — I think we ought to place the Ascoceratide next the 
Cyrtoceratide or between the Cyrtoceratide and the Poterioceratidee, with which there 
may be some sort of affinity through the irregularly inflated living chamber of the latter. 
1) Genera of Fossil Cephalopods, Proc. Boston Soc. N. H., vol. 22, 1883, p. 278 etc. 
