Art. II. — On a Neiu S-pccies of Dictyonema. 



(With Plates I and II.) 



By T. S. Hall, M.A. 



[Bead March .5, 1891.] 



The first specimen I saw of this fossil was a fragment 

 given to me in 1889 by Mr. Clark, a student in geology at 

 tlie Working Men's College. In company with Mr. G. B. 

 Pfitchard, I paid a visit to Lancefield, where the specimen 

 had been found, and about five miles nortb-east of the town- 

 siiip we found the quarry. The rock is a soft black slate, 

 (lipping at a very high angle, and containing a great deal of 

 iron pyrites, both in nodules, and in disseminated grains. 

 The rock is marked lower silurian on the geological map, 

 and is very near the boundary of the upper .silurian which 

 lies to the eastward We were fortunate in finding numerous 

 fragments of the fossil preserved in a white talcose material 

 and accompanied by graptolites. In turning over a heap of 

 (lehris from the quarry, I found the large slab I have figured 

 covered with mud, but still distinctly showing that I had 

 secured a specimen exhibiting the centre of the polyp-stock. 

 One of the fragments found by Mr. Pritchard fitted on to the 

 larger piece as shown in the lower left hand of Figure I. 



l3ictyonema is closely allied to the graptolites, but the 

 chitinous supporting rod, so characteristic of the latter, is 

 wanting in the former. 



Genus Dictvonema. 



Sub-Order — Gampanulariw ; Order — Hydroida. 



Zittel (" Handb. d. Pal., Bd. I.") gives a definition of the 

 genu.s which I translate as follows : — " Hydrosome, funnel 

 j)annier or fan-shaped, with numerous branches almost 

 parallel, strong, forked and united by cross threads. The 

 ends of the branches are free, and are then set on one side 

 with pointed hydrothecse. The latter appear very perishable 

 and are exceedingly seldom preserved." 



