THOLIASTERELLA. 171 



and cylindrical form of the spicular rays and the less development of the central 

 disc. 



Distribution. — Carboniferous : Upper part of the Lower Limestone series, Law, 

 Low Baidland, Dairy, Ayrshire. (J. Smith, J. Bennie.) 



47. Tholiasterella compacta, Ilinde, sp. nov. Plate VII, figs. 3, 3 a. 



The dermal skeleton of this species is a, thick, perforated plate, consisting of 

 " umbrella- " shaped spicules, with stout conical shafts, and five or six robust, 

 cylindrical transverse rays. These completely fuse and amalgamate with those 

 of adjoining spicules, and they are so closely arranged that only a few small circular 

 or oval apertures are present between the rays. The upper surface of the spicule, 

 forming the exposed surface of the dermal layer, is thickly covered with numerous 

 minute, blunted tubercles. 



This perforated dermal layer is from 1 mm. to 1*3 mm. in thickness, whilst the 

 entering shafts of the spicules in some instances are *3 mm. in length. In a 

 specimen belonging to Mr. John Smith, a portion of the internal skeleton is pre- 

 served in connection with the dermal layer. It apparently consists of relatively 

 large spicules of an irregularly stellate form, the rays are of unequal length, 

 conical, and often furcate at their ends. These spicules are intermingled together 

 without definite arrangement, and the rays are frequently fused at their points of 

 contact with adjoining spicules. 



The complete fusion of the spicules of the dermal layer, and the irregular form 

 of the skeletal-spicules, distinguish this from other species of the genus. 



Distribution.- — Carboniferous : Upper part of Lower-Limestone series, Cunning- 

 ham Baidland, Law Quarry, Dairy, Ayrshire. (J. Bennie, J. Smith.) 



48. Tholiasterella crassa, Hinde, sp. nov. Plate VIII, figs. 5, ha; Plate IX, 



figs. 2, 2 a— 2 b. 



Skeleton consisting of very robust " umbrella " spicules, with conical or elongate 

 cylindrical shaft, and from five to six transverse rays. These rays are cylindrical 

 or conical, straight or curved, horizontal or diverging irregularly from the central 

 disc. As a rule the transverse rays are very unequally developed, some being 

 mere conical points, whilst others in the same spicule are relatively very long. 

 The rays are smooth, and either simple, or w T ith stout, obliquely placed spines, 



