406 HISTORY OF GEOLOGY AND PALEONTOLOGY. 



monographs were contributed by Ducrotay de Blainville 

 (1827) and Voltz (1830). Blainville's monograph begins 

 with a historical review, and proceeds to give an accurate 

 description of numerous species; the monograph by Voltz 

 throws new light on the organisation of the Belemnites. 

 Count Minister (1830), Zieten, Duval-Jonve (1841), Quenstedt, 

 D'Orbigny, and other authors increased the number of known 

 species and arrived at a sharper definition of the different 

 groups of species comprised under the generic name of 

 Belemnite. More recent palaeontological work has broken up 

 the old genus and founded several new generic names. 

 Important contributions to the knowledge of the organisation 

 of Decapodous Dibranchs were made by Owen (1844), 

 Mantell (1848-50), and more especially by Huxley (1864). 

 The connection between the extinct Belemnites and living 

 representatives of the group, the Spirulas and the Sepias, was 

 elucidated by these anatomists. An excellent monograph 

 of the "British Belemnites" by J. Phillips (1865-70) appeared 

 in the volumes of the London Palseontographical Society. 



Arthropods. Palaeontologically considered, the Crustaceans 

 are the most important group in this branch of the animal 

 kingdom. In the year 1822, Brongniart and Desmarest 

 published a Natural History of the Crustaceans, wherein 

 a clear exposition was given of the zoological and geo- 

 logical significance of these remains. Catalogues of the 

 fossil Crustacea were prepared by H. Woodward and Salter 

 (1865 and 1877), and the whole class was handled by 

 Gerstaecker (1866-74) in a thoroughly scientific and critical 

 manner, chiefly from the zoological standpoint (Bronn's Classen 

 und Ordnungen des Thierreichs, vol. v.). 



Among the individual orders, the Trilobites have been of 

 the greatest interest for palaeontologists. They appeared in the 

 older literature frequently under the names Trinuclei (Lhuyd) 

 and Entomolites (Linnaeus), until the name Trilobites, 

 proposed by Walch in 1771, came into general use. In 

 addition to the general work of Brongniart and Desmarest, 

 several treatises on the order of Trilobites appeared during 

 the first half of the nineteenth century : the monograph by a 

 Swedish palaeontologist, J. W. Dalman, in 1826; by an 

 American author, J. Green, in 1832; by the German authors, 

 Quenstedt (1837), H. F. Emmrich, Goldfuss (1843), 



