a Family of Graptolites. 19 



Quebec Group, Canada ; Skiddaw Slates, N. England ; Arenig, 

 Australia ; Middle Arenig, Wales ; Phyllograptus-shdiXes, Norway, 

 Dalecarlia ; Tetragraptus-zone, Skane. 



2. Tetragraptus Halli, Hopk. and Lapw. 

 Middle Arenig, Wales. 



3. Tetragraptus Hicksii, Hopk. and Lapw. 

 Middle Arenig, Wales. 



4. Tetragraptus serra (Brongn.), (Gein.), Hopk. and Lapw., Tornq. 



Facoides serra, Brongn. 

 Cladograptus serra, Gein. 

 Graplolithus bryonoides, Hall. 

 Tetragraptus bryonoides, Salt., Nich. 

 Didymograptus bryonides, Carr., M'Coy. 



Arenig and equivalents in Wales, N. England, Canada, Norway, 

 Skane, Westgothland, and Dalecarlia; Newfoundland. 



5. Tetragraptus denticulatus (Hall), Lapw. 

 Quebec Group, Canada; Silurian, Victoria ? 



6. Tetragraptus crucifer (Hall), Nich., and Lapw. 

 Witb a central disc. 



Quebec Group, Canada; Skiddaw Slates, N. England. 



7. Tetragraptus alatus (Hall), Lapw. 

 Witb a central disc. 



Quebec Group, Canada. 



8. Tetragraptus Headi (Hall), Nich., Lapw. 

 Witb a central disc. 



Quebec Group, Canada ; Newfoundland ; Lower part of Skiddaw 

 Slates, N. England. 



9. Tetragraptus caduceus (Salt.). 



Didymograptus caduceus, Salt., Nich., M'Coy. 

 Phyllograptus similis, Hall. 

 Graptolithus Bigsbyi, Hall. 

 Tetragraptus Bigsbyi, Linnars., Lapw. 



Skiddaw Slates, N. England; Quebec Group, Canada; Phyllograptus- 

 sbales, Norway, Skane ; Australia (Etber., Ann. Mag. N. H. ser. 4, 

 vol. xiv. pi. iii. figs. 3, 4). 



10. Tetragraptus approximates, Nich., Lapw. (Woodcut, p. 17, 

 Fig. 5.) 



Quebec Group, Canada; Phyllograptus-sheiles, Norway. Norwegian 

 specimens differ in not having the branches so close together as in 

 Nicholson's figure ; the curvature on both sides of the branches is 

 sharper, and the branches do not so soon become parallel, and do not 

 continue so exactly parallel as Nicholson indicates. One specimen 

 from near Fure, in Kingerike, showed traces of a central disc. 



Group /3. 



11. Tetragraptus fructicosus (Hall), Lapw., Brogg., Herrm., Tullb. 



Graptolithus fructicosus, Hall. 

 Didymograptus fructicosus, Ether., M'Coy. 



Quebec Group, Canada ; Llandeilo Flags, Australia ; Phyllograptus- 

 shales, Norway ; Tetragraptus-zone, Skane ; Arenig, Australia 

 (according to Lap worth). 



