GLOSSOGRAPTUS. 313 



flexed. Thecae nine in 10mm., overlap very slight; apertural margins 



slightly everted ; apertural spines somewhat slender and rigid ; septal spines 



straight and stiff. 



Description. — The polypary is characteristically small, and the spines are more 



distant from each other than in other species belonging to the genus. These 



spines are slender and somewhat rigid, and are commonly about 2 mm. in length, 



though they may be as much as 3 mm. The septal spines are somewhat similar 



in size and form, but are straighter and more rigid. 



The sicula is not visible, though its position is indicated by a conspicuous 

 Fig. 2M.-Giossogra.ptus armaius, Nich. virgella, which has a length of about 1 mm. Th. I 1 



and th. 1~ are, in addition to their apertural spines, 

 provided with very long curved mesial spines, about 

 4 mm. in length, which originate at the point where 

 the thecae change their direction of growth from 

 horizontal to upward and outward, and these curve 

 down so that their extremities are nearly parallel to 

 the virgella. These spines seem to be a prolonga- 

 tion of the thickening of the earlier parts of the 

 lower walls of th. I 1 and th. I 2 , and show as almost 

 continuous lists across the polypary. 

 Proximal end, showing two sets of spines The type specimens of Glossoa. armatus, which 



on th. I 1 and th. 1-. Enlargement •/ r i ./ 



of part of pi. xxxiii, fig. 5 d. came from Thornship Beck in the Lake District, are 



very indifferently preserved, especially as regards the proximal end, and the present 

 description has been drawn up from much better preserved examples from Morrach 

 Bay, South Scotland, which are believed to be referable to Nicholson's species. 



Affinities, etc. — Glossog. armatus presents a certain resemblance to small 

 examples of G. HincJcsii, but it differs from it in the size of the polypary, the more 

 distant thecae, and the long basal spines. From G. HincJcsii var. fimbriatus it 

 differs in the number of thecae and the presence of the long curved spines at the 

 base. 



Horizon and Localities. — Llandeilo, Glenkiln Shales ; and Upper Skiddaw Slates 

 (Ellergill Beds). 



8. Scotland : Back Burn, Crawick Water ; Polmorlach Burn, Dumfries ; 

 Stream 1^ miles E. of Manwhill Head, Waters of Ken; Kirriereoch Burn, and 

 Kinniemore Burn, Water of Minnoch. Lake District ; Thornship Beck. 



Associates. — In the Upper Skiddaw Slates Glossog. armatus occurs in the 

 Ellergill Beds associated with Glyptog. dentatus. In the Glenkiln Shales it occurs 

 with Didymog. superstes, Nemag. pertenuis, and Dicranog. celticus. It is a rare fossil. 



Collections. — Geological Survey of Scotland, Sedgwick Museum, British Museum 

 (Natural History). 



41 



