Prcsidmit's Address. 77 



have the outer shell well preserved, whilst OrthoccratUcs 

 even retain traces of chevron-shaped bands of colour. * 



The special bibliography of the Scotch Carboniferous 

 Cephalopoda is of the most limited description. Tlie first to 

 describe members of this Class after the Eev. David Ure was 

 Professor Fleming, who furnished descriptions of no less 

 than ten species.f 



As specially relating to Carboniferous Cephalopoda, we 

 must not omit to mention the first and second parts of the 

 magnificent work by Professor de Koninck referred to when 

 treating of the Gasteropoda.^: The same sumptuousncss of 

 illustration and fulness of description is carried out, and 

 will allow the future determination of species to be a task 

 of greater ease and pleasure. 



The large Family Orthoceratida? contains the genera Adino- 

 ceras (Bronn), Cyrtoccras (Goldfuss), Orthoccras (P)reynius), 

 Aploceras (D'Orbigny), etc. 



The unwieldy genus Orthoceras is largely represented in 

 Scotch Carboniferous Limestone beds, no less than twenty- 

 two species having at one time or the other been described 

 or listed. The names of many of these will doubtless prove 

 to be synonyms ; some certainly are now known to be so. 

 No shells, except perhaps the Goniatites, are so difficult of 

 correct determination as those of the present genus. Some- 

 times found as casts, often in fragments, and differing as they 

 do in various parts of their length, it is at times extremely 

 difficult to draw the line where one species commences and 

 the other ends. This difficulty is not lessened by the loose 

 manner in which many of the descriptions have been drawn 

 up. 



Professor M'Coy employed several sectional names under 

 Orthoceras for the limitation of the species. Two at least of 

 these are equivalent to the genera of other observers, whilst 

 two others may perhaps be employed in the manner sug- 



* W. Scot. Fossils, p. 58. 



t "Observations on the Ortlioceratites of Scotland" (Thomson's Annals 

 Phil., 1815, v., p. 199). 



X Annales du Musec R. d'Hist. Nut. dc Belgiipic, v.; Faune dn Calc. Cai- 

 bonif. de la Belgiquc, 1™*-^ partic. 



