STJPPLEME>’T. 
387 
mentioned these fossils in their memoirs or miiniials (viz., Billings, 
Giehel, AViltshire, Wright, Blake, Zittel, and Boord) have placed 
the Ascoceratidce close to Gomphoceras. This has in some respects 
been caused by the accidental similarity of the truncation, and in 
some degree by the inflated shell in these genera, which also seems 
to have led some authors to accept the idea that Ascoceras^ and still 
more Aplinujmites, was in its entirety the living chamber of the 
animal. Ferd. Boemer places Ascoceras next to Troclioceras, Bronn 
and Woodward next to Gyroceras^ Philippi between Litidtes and 
Ciirioceras, while iSiicholson includes it within his family of the 
Orthoceratidcv. 
Hyatt, disregarding the fundamental similarity in structure, 
placed his own genus Billinysites amongst the Mesoceraiidce and 
the other genera in the family of the Ascoceratidcc, and both these 
families next each other between the Gomplioceratidce and the 
McdonocercUidte. There is no valid ground to separate Billinysites 
from the Ascoctratidce, and join it with 2Iesoceras. This latter 
genus, which was founded by Barrande on a single specimen — none 
having since his day been found — is known only by the living 
chamber, which closely resembles that of the Gomphoceratidm, with 
which group also Fischer and Foord have united it. There is no 
evidence whatever [in i\Iesoce7'as'] of septa like those of Ascocei'as, 
and there is consequently no foundation for placing it with the 
Ascoceratidan genus Billinysites. 
Hyatt also included Ophidioceras amongst the Ascoceratidce,, 
because “ the costated compressed whorls have some resemblance to 
those of Ascocei'as^ 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 significance when 
the most important character, the sigmoid septa, is wanting. The 
arrangements of Hyatt must then be changed thus, — that Billinysites 
is to be placed amongst the Ascocei'atidce near Glossoceras, on account 
of its contracted aperture, while Ophidioceras may keep its more 
natural place, which has been given it by Barrande, amongst the 
Litaitidce. Strangely enough, Hyatt has re-established Aphray- 
mites in spite of its disavowal by its own author, Barrande. Hyatt 
thinks “ it is a distinct genus with simple septa and sutures.” 
According to Barrande its chief characteristic should, however, con- 
sist in its total want of septa, which also is indicated by its 
name. 
Ascoceras . — This remarkable genus is during a long period of its 
life Hautiloid as to the structure of its shell, and at last changes into 
2c2 
