CONCLUDING REMARKS. 221 



therefore be found to be remedied to a large extent in the complete work, the 

 publication of which, owing to the lamented death of its accomplished author, has 

 naturally lapsed, we trust only for a time. 



As the greater part of the present Monograph had appeared before Eastman's 

 ' Translation ' was published, I was unable to make use of Hyatt's revised classifi- 

 cation contained in it, which is here briefly outlined. As in the ' Genera of 

 Fossil Cephalopods,' the structure of the siphuncle constitutes the leading feature 

 of the larger divisions (sub-orders) of the Nautiloidea. Those forms having long 

 septal necks or " funnels " which completely close the spaces between the septa, 

 Holochoanites, include Endoceras, Piloceras, and other genera. Under the sub-order 

 Mixochoanites, Ghoanooeras, Ascoceras, Mesoceras, etc., are placed. Gonoceras, with 

 some other aberrant genera, is put into the sub-order Schistochoanites. Ortho- 

 choanites includes a great number of genera, of which only a few can be named : 

 Orthoceras, Lituites, Glydonautilus, Vestinautilus, Hercoceras, Solenocheilus, Acantho- 

 nautilus, Nautilus, and many others. Under Cyrtochoanites (in which the shortness 

 of the septal necks is the leading feature), Loxoceras, Adinoceras, Ooceras, Poterio- 

 ceras, Gompliocerux, I'linnjinocrras, and other genera are comprised. 



In the Ammonoidea we are here concerned only with the primitive group of the 

 Goniatites ; these are arranged by Hyatt, together with the Ammonites, under new 

 sub-orders, as follows: — Gastrocampyli 1 ( = Glymenia of former systems), Micro- 

 campyli, Mesocampyli, Eurycampyli, Glossocampi/U ( = Goniatites [excepting 

 Prolecanitidse] of former systems), Discocampyli ( = Ceratites of former systems), 

 Phyllocampyli (including Prolecanitidge, Noritidas [Waagen], Medlicottidae), 

 Leptocampyli, Pachycampyli ( = Ammonites of former systems). 



Gastrocampyli is the equivalent of von Zittel's Int/rasiphonata ; the rest of the 

 sub-orders are naturally included in his Extrasiphonata. 



The method of arrangement of the species described in this Monograph may now 

 be explained. The subdivisions of the Orthoceratidas proposed by Hyatt in his 

 provisional classification contained in the 'Genera of Fossil Cephalopods,' and 

 founded mainly upon the external features of the shell, its ornamentation, shape, etc., 

 met with only partial acceptance, owing to the difficulty of strictly limiting the 

 genera, especially when forms of a transitional character had to be dealt with. It 

 was therefore not adopted in this Monograph, in which the Orthoceratidae are 

 primarily divided into Longicones and Brevicones* the former being again divided 

 into groups and sub-groups according to the ornamentation of the test and the 

 structure of the siphuncle. In this group the septation appears to he the least 

 useful of the characters to be employed to differentiate its various elements, the 



1 "The suffix camypylws, signifying curve, in the names of the sub-orders, is used wholly with 

 reference to the saddle inflections as they appear in the typical forms of each group." 



2 Barrande, 'Syst, Sil. de la Boheme,' vol. ii, Texte, l 6re Partie, luvh. Pal., L867, p. *. 



