Lapworth— Graptolites of Co. Down. 129 



14. Sp. 9. Monograptus lobiferus. M'Coy. PI. 5, fig. 6. 



This species occurs in the black shales of Coalpit Bay in a few o f the com- 

 mon varieties, in all of which the extremity of each theca seems to form a 

 rounded lobe, the aperture being apparently directed partly inward and partly 

 upward against the lower wall of the central portion of the tube. According 

 to Dr. Linnarsson, who has found specimens of this species in the lobiferus 

 schists of Sweden, preserved in relief, the hydrotheca is actually coiled obliquely, 

 and thus the aperture opens outward in a different plane to that of the 

 proximal portion of the theca, which is wholly free. Locality — Coalpit Bay. 



In the grey schists of Tieveshilly this species appears to be represented by 

 the following form : — 



15. Var. pandus. Lapw. Var. nov. PI. 6, fig. 3. 



Polypary simple, monoprionidian, stout, straight ; from four to six inches 

 in length, and with an average diameter of % of an inch in the fully 

 developed portion, inclusive of the projection of the hydrothecse. 

 These are arranged in the proportion of from 24 to 28 to the inch, and 

 are in contact only. They are broad at their origin, and have the 

 superior margin almost horizontal. They narrow rapidly towards 

 their outer extremity, which is bent downwards in the direction of 

 the proximal extremity of the polypary. 



This form has been frequently noticed by paleeontologists, but its distinct- 

 ness has not hitherto been acknowledged. Barrande (Grapt. de Boheme. PI. 1, 

 figs. 10 to 14) and Geinitz (Die Graptolithen, Taf. Ill, figs. 24, 25, &c.) both 

 refer it to Monograptus priodon. (Bronn). From that species, however, it is 

 easily distinguished by the general form of the theca, and the absence of 

 overlap. From Monograptus Clingani (Carr.) it differs in the size and shape of 

 the polypary. Locality— Tieveshilly. 



16. Sp. 10. Monograptus priodon. Bronn. PI. 5, figs. 24a, and 24b. 



Locality — Tieveshilly. 



17. Sp. 11. Monogtaptus Riccartonensis. Lapw. PI. 5, fig. 23. Locality— 



Tieveshilly. 



18. Sp. 12. Monograptus Galaensis, ;Lapw. PI 6, fig. 1. Locality — 



Tieveshilly. 



