Prof. F. M r Coy on some new Devonian Fossils. 481 



alone being quite sufficient to convince the observer that no such 

 dehiscence as that represented by Vaucher could take place." (!) 

 I shall hope in a few weeks, when the Alga is in a more ad- 

 vanced state, and the process fully completed, to detail the cir- 

 cumstances attending it at greater length ; in the mean time I 

 hasten, not merely to record a fact of importance to the algolo- 

 gist, but to redeem from an undeserved censure the reputation 

 of an observer, whose admirable writings were among the first to 

 direct attention to a department of nature which had previously 

 been treated with comparative neglect. 



Yours respectfully, 



William Smith. 



XL. — On some new Devonian Fossils. By Frederick M'Coy, 

 Professor of Mineralogy and Geology, Queen's College, Belfast. 



Steganodictyum (M'Coy), n. g. 

 Etym. Sreyavo?, covered, and hUrvov, a network. 



Gen. Char. Polymorphous, forming either narrow, rounded, 

 branch-like masses, or extended into thin, flat, foliaceous ex- 

 pansions ; the interior of all the forms composed of rather 

 large, irregular, polygonal or subhex agonal cells, the three 

 dimensions of which are approximately equal (commonly about 

 half a line in diameter), which become rapidly smaller towards 

 the exterior, blending with the dense covering of the surface, 

 which is variously sculptured with close waving lines, tuber- 

 cles or costse according to the species ; surface dense, forami- 

 nated by the contracted, rather distant openings of the small 

 cell-mouths. 



These curious zoophytes abound in a particular layer of dark 

 Devonian schist near Polperro on the coast of Cornwall, 

 and are the bodies which have been taken for fossil fishes by 

 all previous observers — the thick reticulated fragments being 

 quoted as " bones of Aster olepis ;" flat sculptured portions 

 being taken for the scaly parts of various fishes, and the midribs 

 of some of the fronds being supposed to be " Ichthyodorulites, 

 as Diplacanthus, Ctenacanthus, and Upper Silurian species of 

 Onchus." The supposed correctness of the latter identifications 

 induced Sir R. Murchison to colour the part of the Cornish 

 coast where these fossils occur as Upper Silurian, in his last map 

 of that region. I first examined a good suite of these supposed 

 Cornish fossil fishes at the Museum of Economic Geology, Jer- 

 myn Street, in company with Prof. Sedpwick last July, and at 

 once demonstrated their true nature to Mr. Salter, who was kind 



Ann. fy Mag. N. Hist. Scr. 2. Vol.\\\\. 31 



