HISTORY OF RESEARCH. ixxxi 



1873. 



Malaise, In the same year Malaise recorded the existence of the 



" Note sur la descrip- second Silurian Fauna, containing Glimaco. scdlaris and 



tiondu terrain Silurien Graptolithus priodon in the Upper part of the Silurian 



„ , . „ . "terrain "in the centre of Belgium; the fossiliferous horizons 



Uelgique, ' Ann. Soc. 

 Malacologique de la representing the Upper Caradoc and Lower Llandovery. 



Belgique,' t. 8. 



1873. 



Lapwortlt , 



" Notes on the British T ., 0( _ T jn , ,. , . . . _. 



. ... , ,, . In 18/o Lapwortn published a comprehensive paper Un 



Grraptolites and their l r l l l 



Allies. On an an Improved Classification of the Rhabdophora." 



Improved Classification 

 of the Rhabdophora," 

 ' Geol. Mag.' vol. x. 



Classification. — Accepting Allman's term Rhabdophora as the collective term 

 for all the presumed virgula-bearing Graptolites, Lapworth separates them into 

 two sections, namely : 



Section I. — Graptolitidae (or Graptoloidea), in which the polypary is 

 developed from a true sicula, the ccenosarc originates a single series of theca? 

 only, and the virgula is dorsal and on the exterior of the periderm. 



Section II. — Eetioloidea, in which the polypary is not developed from a siculi- 

 forin "germ," the ccenosarc originates a double series of theca^, and the epiderm is 

 more or less supported by a framework of chitinous filaments. 



The Gkai'Toloidea are divided into six families : 



1. Monograptidse, distinguished by the nucleated arrangement of the parts. 

 Genera: 1, Bastrites ; 2, Monograptus ; 3, Cyrtograptus. 



2. Nemagraptidae (Hopk. MS.), slender forms, with ornate thecae and irregular 

 branches. Gen.: 4, Leptograptus ; 5, Amphigraptus ; 0, Nemagraptus ; 7, 

 Co&nograptus. 



3. Dichograptidae, regularly branched, with prismatic theca\ Gen. : 9, Didy- 

 mograptus ; 10, Tetragraptus ; 11, Dichograptus ; 12, Loganograptus ; L3, Clono- 

 graptus ; 14, 15, 1(5, 17 (unnamed). 



4. Dicranograptidae, two-branched, with incurved thecae. Gen. : 18, Dirello- 

 graptus ; 10, Dicranograptus. 



5. Diplograptidae, polypary duplicate. Gen.: 20, Climacograpftis j 21, J>ifh>- 

 graptvs. (Subgenera : Glyptograptus, Petalograptus, Cephalograptus, Ortho- 

 graptus.) 



0. Phyllograptidae, polypary composite, quadribrachiate. Gen.: 22, Phi/llo- 

 graptus. 



The Retioloidea are divided into two families: 



/// 



