DOUBTFUL SPECIES. 181 



the Lower-Ludlow strata of Leintwardine, and the originals were stated to be in 

 the Ludlow Museum, but they cannot now be found. I had been in correspond- 

 ence with Dr. Holl shortly before his death respecting these types, and, acting on 

 a suggestion made by him, I examined, by the kind permission of Prof. Boyd 

 Dawkins, F.R.S., the Lightbody collection, now in the Museum of Owens College, 

 Manchester, but without meeting with them. Their loss is the more to be 

 regretted since no other specimens corresponding with Dr. Holl's descriptions 

 have been discovered, and his species will therefore lapse. It seems to me pro- 

 bable that Protospongia Ludensis may have belonged to the genus Dictyophyton, and 

 P. maculceformis to Phormosella. 



67. Pulvillus Thomsonii, Garter. 



1878. Annals and Mag. Nat. Hist., ser. 5, vol. i, p. 137, pi. z, figs. 1- 



-G. 



I am indebted to Mr. James Thomson, F.G.S., for the opportunity of examining 

 the type forms of this new genus and species. The specimens are bi-convex or 

 plano-convex discs with occasionally a depression on one or both surfaces. They 

 are composed of rounded or amorphous grains of calcite, from 1 to 3 mm. each 

 in diameter, closely aggregated together, so that in a section but little more than 

 the partition line between the individual grains is visible. In some cases the 

 grains are separated by rock matrix from each other. There are no traces of 

 Sponge-fibres of any kind nor of canals. The constituent grains of calcite in part 

 exhibit an acicular or fibrous crystalline structure, which is regarded by Mr. Carter 

 as indicating acerate Sponge-spicules (loc. cit., pi. x, fig. 4). 



Further, the objects represented as "broken ends of the spicules projecting 

 from the surface of the large excavation " in the type-specimen appear to me to 

 be punctures in a fragment of the shell of some Brachiopod (L c, pi. x, fig. 6). 

 The acerate spicule, figured as the staple form of a perfect spicule (7. c, pi. x, 

 fig. 5), is derived from the sandy material of the rock matrix, and there is no 

 evidence beyond its position that it had any relation to the supposed Sponge. 



These bodies in my opinion are merely nodules of inorganic origin. They are 

 from Carboniferous Limestones at Arbigland, near Dumfries. 



68. Sctphia tuberculata, King. 



1850. Mon. Permian Toss., Pal. Soc, vol. iv, p. 12, pi. ii, figs. 1, 2. 



The type-specimen, now in the Museum of Queen's College, Galway, is a 

 fragment of a cylindrical body, with a hollow axial tube and lateral tubes partly 



