Trof. H. A. Nicholson — New Devonian Fossils. 15 



new series, vols. iv. and v.). To these I have now to add five 

 species from the Corniferous Limestone, and a sixth from the 

 Hamilton shales, all of which appear to be distinct from previously 

 described forms. 



Alveolites frondosa, Nicholson. Plate II. Fig. 2. 



Spec. char. — Corallum forming elongated, sometimes palmate ex- 

 pansions, which appear to have grown in an erect position from a 

 rooted base, and which carry calices on both sides. The width of 

 these expansions seems never to have been over an inch and a 

 quarter, often less, and the thickness rarely exceeds two lines, 

 whilst the height is unknown, but certainly sometimes exceeded 

 two inches. The corallites spring from the median plane of the 

 frond on both sides, and are very oblique to the surface. Walls of 

 the corallites exceedingly thick; calices small, transversely oval 

 or subtriangular, arranged in oblique lines, their long diameter being 

 not more than from one-fourth to one-third of a line, with a trans- 

 verse diameter one-half less. The inferior lip of the calice is thin 

 and prominent, but there are no traces of any internal ridge or tooth. 

 The calices are separated by intervals of about one -third of a line 

 in the vertical direction of the frond, and one-fourth of a line, or 

 less, in the transverse direction of the frond. 



There can be little question as to the distinctness of this not un- 

 common species. It is readily distinguished from all other species 

 of the genus except A. Fischeri, Billings, by its peculiar form and 

 mode of growth, and it is separated from this by the very much 

 smaller size of its corallites, and their much closer arrangement. 

 From the thickness of the walls of the corallites in this, as in some 

 other forms from the Devonian rocks of Ontario, the appearance is 

 produced of the corallites being imbedded in a more or less abundant 

 coenenchyma, which, however, has no true existence. For this 

 reason, also, the aspect of the fossil differs in some degree from 

 that of the typical species of Alveolites, and more or less resembles 

 that of Coenites, Eichwald [=Limaria, Steininger), from which it 

 is separated by the absence of calicinal teeth. 



Locality and Formation. — Common in the Hamilton formation 

 at Bartlett's Mills near Arkona, township of South Williams. 



Alveolites Selwynii, Nicholson. (Fig. 3.) 

 Spec. char. — Corallum forming an irregularly-shaped crust, or 

 depressed mass, about one line in thickness. The corallites are 

 exceedingly oblique to the surface, and open by calices which have 

 the form of curved or lunate slits, the length of which is about 

 three-quarters of a line, whilst their width in the centre is only 

 a tenth of a line, or thereabouts. The calices are placed in ir- 

 regularly alternating lines, or sometimes in an indistinctly sub- 

 spiral manner, and are about half a line or three-quarters of a line 

 apart, the thickness of the walls of the corallites being thus very 

 considerable. 



This curious form belongs to the same section of Alveolites as 

 A. suh-orhicularis, Lam., A. Goldfussi, Billings, and A. depressa, 



