i34 Lapworth — Graptolites of Co. Down. 
regularly disposed in two opposite series, and sometimes irregularly scattered 
along tlie extent of the outer margin of the polypary. 
These forms are all certainly allied to Glossograptus , but our present 
evidences are insufficient to justify their removal to that genus. Locality — 
Camalea. 
47. Sp. 15. Diplograptus Whitfieldi. Hall. PI. 6, fig. 21. 
The interesting examples furnished with lateral reproductive appendages, 
figured by Hall in his Graptolites of the Quebec group, Plate B, and assigned 
by him to the present species, are clearly distinct. It is most probable that 
they belong to a form of Lasiograptus (?) resembling Lasiograptus 
bimucronatus , Nich. Locality — Carnalea. 
48. Sp. 16. Diplogr aphis (Lasiograptus 1 ) mucronatus. Hall. PI. 6, fig. 22. 
In this series the apertural fibres occasionally anastomose; and examples 
with lateral reproductive appendages are not infrequent in the Moffat Series in 
Scotland. In Ireland the species is as yet unknown. 
49. Sp. 17. Diplograptus ( Hallograptus) bimucronatus. Nich. PI. 6, fig. 23. 
It is in this species that the lateral reproductive processes are most 
frequently met with in British Rocks. Few examples of this form occur which 
appear wholly destitute of them, or of the lateral fibres which support them. 
Mr. W. Carruthers has suggested that this form, and the very similar 
Diplograptus mucronatus should be erected into a new genus under the title of 
Hallograptus , in honour of the eminent palaeontologist, who was the first to 
figure these forms and to suggest the possible function of their remarkable 
appendages. 
Genus VI. Glossograptus. Emmons. 
50. Sp. 1. Glossograptus Hincksii. Hopk. PI. 6, fig. 24. 
The lateral appendages in this species and genus differ from those in 
Hallograptus , in being rigid blind spurs comparable with those at the proximal 
extremity of Climacograptus bicornis (Flail). In all the supposed species of this 
genus, the apertural spines are also remarkably stout and rigid, but they never 
anastomose as in the older and very closely allied genus Retiograptus of Hall. 
(Grapt. Quebec Group, Plate 16, figs. 6 to 8). Glossograptus ciliatus , Emmons 
(American Geol.^vol. 1, plate 1, fig 25); Glossograptus setaceus , Ibid. Fig. 
