402 HISTORY OF GEOLOGY AND PALEONTOLOGY. 



Individual classes, orders, or families have sometimes been 

 made the subject of special study. A notable monograph is 

 that by Coquand on the Ostreacese of the Cretaceous forma- 

 tion (1869), and several monographs have been devoted to 

 the consideration of the Cretaceous family of the Rudistes. 

 Neumayr in 1891 proposed a classification of the Lamelli- 

 branchia based upon the characters of the hinge, and Jackson 

 and Bernard endeavoured to make the developmental history 

 of shells and hinge useful for systematic distinctions. 



The literature on fossil Cephalopods is almost too extensive 

 to be reviewed. As far back as 1798, Cuvier had united all 

 the Cuttle-fishes, together with Nautilus and the Foraminifera 

 in one group, which he named Cephalopoda, and ranked as a 

 distinct class clearly differentiated from all other molluscs. 



The anatomy and morphology of cuttle-fishes was carefully 

 studied by Cuvier and Delia Chiaje, and the brilliant ana- 

 tomical researches of Owen (1832) on the Pearly Nautilus 

 afterwards gave a clear insight into the relationships of the 

 Cephalopoda. Owen sub-divided the Cephalopoda into two 

 orders, the Tetrabranchiata with two pairs of ctenidial gills, 

 and the Dibranchiata with a single pair of ctenidial gills. To 

 the Tetrabranchs, Owen assigned, in addition to Nautilus and 

 the fossil Nautilites, the large assemblage of the Ammonites. 

 Lamarck in 1801 had differentiated the genera Nautilus, 

 Orbulites, Ammonites, Planulites, and Baculites, and had 

 pointed out the difference between the sutural lines of the 

 chamber divisions in Nautilus and Ammonites. Denys de 

 Montfort (1808), Sowerby, and Parkinson added a few more 

 Cephalopod genera, and De Haan in 1825 classified the 

 known genera under three families (Ammonitea, Goniatites, 

 and Nautilea). 



Marked advance was effected by the investigations of 

 Leopold von Buch (1829 and 1839). According to the 

 position of the siphuncle, Buch distinguished two chief groups, 

 Nautilidas and Ammonitidse, and sub-divided the latter accord- 

 ing to t-he form of the sutural line into the three sections, 

 Goniatites, Ceratites, and Ammonites. Buch introduced a 

 precise terminology for the various parts of the sutural 

 lobes; he distinguished fourteen families, partly in accordance 

 with the shape and decoration of the shell, partly in accord- 

 ance with the sutural lines. The spirally-rolled forms were 

 contrasted by Buch with the straight Baculites and the 



