PLATE VIII. 



Figs. 1, la—1 h. — Spibactinella Wbightii, Carter, sp. 



Fig. 1. — A large skeletal-spicule in which the distal ray and the four transverse rays are bifurcate. 



Figs. 1 a, 1 b. — Smaller skeletal-spicules with simple rays. 



Fig. 1 c. — A skeletal-spicule in which all the rays are furcate. 



Figs. 1 d, 1 e. — Small six-rayed spicules in which each of the rays are divided at their extremities. 



Figs. If, Iff, 1 /*. — Stellate spicules resulting from the bifurcation of six-rayed spicules. 



The specimens are all drawn to the same scale of forty diameters. From decayed chert in Carbo- 

 niferous Limestone at Ben Bulben, Sligo, Ireland. The original specimens in the collection of Mr. 

 J. Wright, F.G.S., of Belfast, with the exception of 1 d, 1 e, which belong to Mr. H. J. Carter, F.E.S. 



Figs. 2, 2 a — 2g.— Holastebella confeeta, Carter. 



Figs. 2, 2 a — 2 d. — Fragmentary six-rayed spicules of the skeleton, free or partially cemented 

 together. 2 a is magnified forty diameters, and the others twenty diameters. From Lower Carboni- 

 ferous, highest bed of the Upper Limestone series, near Dairy, Ayrshire. The original specimens in 

 the collection of Mr. H. J. Carter, F.E.S. 



Figs. 2 e, 2/, 2ff. — Small stellate spicules. Magnified forty diameters. From the type-specimen 

 in the collection of Mr. James Thomson, F.G-.S. 



Figs. 3, 3 a — 3 h. — Asteeactinella expansa, Hinde. 



Figs. 3, 3 a — 3 d. — Various forms of skeletal-spicules. With the exception of 3 c, which is magni- 

 fied twenty diameters, the spicules are enlarged ten diameters. 



Fig. 3 e. — A corolla-like spicule, showing the upper surface. Magnified twenty diameters. 



Fig. Zf. — A similar spicule, showing the under surface. Magnified ten diameters. 



Figs. Sff, 3 h. — Small irregular stellate spicules. Magnified twenty diameters. 



From the Lower Carboniferous, upper part of the Lower Limestone series, at Law Quarry, Dairy, 

 Ayrshire. The original specimens in the collection of Mr. J. Smith, Kilwinning. 



Figs. 4, 4 a — 4>i. — Acanthactinella Benniei, Hinde. 



Different forms of detached skeletal-spicules. Enlarged ten diameters. Lower Carboniferous, 

 upper part of the Lower Limestone series, at Law Quarry, and Cunningham Baidland, Dairy, Ayrshire. 

 The original specimens in the collections of Mr. J. Smith, Mr. J. Young, F.G-.S., and Mr. J. Bennie. 



Figs. 5, 5 a. — Tholiastebella ceassa, Hinde, sp. nov. 



Two detached skeletal-spicules. Enlarged ten diameters. Lower Carboniferous, lower part of 

 the Lower Limestone series, Crawfield Quarry, Beith. The original specimens in the collection of Mr. 

 J. Young, F.G-.S. 



