DOUBTFUL SPECIES. 177 



to the different British species of Stromatopora, formerly regarded ns Sponges, 

 since the Monograph on these fossils by Prof. Dr. H. A. Nicholson, F.L.S., 

 now in course of publication, shows clearly their true relationship to the Hydrozoa. 

 The species enumerated below are placed in alphabetical order. 



52. ACANTHOSPONGIA SlLURIENSIS, M'CoiJ. 



1862. A Synopsis of the Silurian Fossils of Ireland, p. 67. 



The typical form is described as a " lengthened oval mass, about two inches 

 long and three quarters of an inch wide, of crowded spicula varying in length from 

 two lines to more than half an inch. The spicula resemble the letter X in shape, 

 four of the rays being always very distinct and disposed in that form, but there 

 also seems to have been certainly one similar ray extending upwards and another 

 downwards from the centre, considering the other four to be horizontal. The rays 

 are round, tapering, pointed, smooth, and apparently hollow. They remind us 

 much of Xanthidium and those allied forms, but have obviously a stronger affinity 

 with the group in which I have placed them, although I do not think I have seen 

 even among any of the foreign Sponges such strong, star-like spicula." 



No figure accompanies the description, and from this alone it is impossible to 

 form an idea either of the form of the spicules or of their arrangement in the 

 Sponge. Unfortunately, the type-specimen, which was in the collection of the 

 late Sir R. Griffith, cannot now be found. It does not appear to have reached 

 the Natural-History Museum in Dublin, in which the greater part of Sir R. 

 Griffith's collection is now preserved, and nothing is known of it in the collection 

 of the Geological Survey of Ireland. No other specimen corresponding toM'Coy's 

 description has been discovered, and therefore the genus and species must lapse, 

 at least for the present. There can hardly be a doubt that the original was a 

 genuine Sponge, but whether it resembled Protospongia or the genus which I have 

 named Phormosella cannot be determined. The type-specimen was from sandstone 

 at Cong, near Galway, Ireland. 



53. Astylospongia sp. (grata, Salter MS.) 



1873. Cat. Cambrian and Silur. Foss. Cambridge, p. 40. 



The original specimen, now in the Woodwardian Museum at Cambridge, is 

 stated to be one of the lobed Sponges, but in reality it is only a cast, exhibiting ten 

 ridges radiating from a common raised centre. Its character is doubtful ; it may 

 be the impression of the summit vault of a crinoid. 



