No. 7.] DAWSON — NEW FOSSILS. 413 



triangular space into three equal parts. There are indications 

 of a slight internal transverse rib near the anterior end, suggest- 

 ing affinities with King's genus Pleiirophorus. It is nearly 

 allied to S. pUcafus of McCoy. Length of the largest specimen 

 3.5 centimetres. 



Lower Carboniferous Limestones at Brookfield and Windsor. 



AvicuLOPECTEN Lyelli, (var. altertians.) 



In describing the Aviculopectens of the Lower Carboniferous 

 (Acadian Geology, pp. 305 to 307), I have mentioned specimens 

 resembling A. Lyelli, but larger and more coarsely marked, 

 and which I compared with ^1. pUcatus of Sowerby. Many 

 additional specimens of these shells, collected from time to time, 

 appear to show gradations connecting them with the typical A. 

 Lyelli, which they perfectly resemble in general form and general 

 style of markings, but differ in larger size and in having broader 

 ribs, nodose rather than squamous, and generally showing toward 

 the edge alternations of coarser and finer ribs. The larger and^more 

 characteristic specimens of this form might readily be considered 

 distinct ; but intermediate forms seem to show that there is no 

 specific distinction. My best specimens are from the limestones 

 of Brookfield and the Shubenacadie. 



Berenicea INSUETA, S.N. 



Group of cells oval, about one millimetre in length and some- 

 what raised in the centre ; on the dorsal valve of a shell of Atliyris 

 subtilita. Cells round, spirally arranged, somewhat oblique to 

 the surface. Spaces between cells granular. About ten cells in 

 the length of the group. 



Encrusting Polyzoa of this kind appear to be rare in the Car- 

 boniferous limestones of Nova Scotia. The present species occurs 

 in Prof. Hartt's collection from Windsor. 



3Iegastroma LAMINOSUM, S.N. 



Broadly expanded layers about one millimetre in thickness, 

 and two millimetres or more apart. Each layer consists of a 

 double membrane, beset with numerous spicules pointing inwards 

 and lookinsr like two brushes facinii' each other. The membranes 

 are penetrated by openings or oscula, and appear to be porous or 

 reticulate in their substance and to have cellular thickenings in 

 places, giving them a peculiar appearance. The layers sometimes 



