142 BRITISH PALEOZOIC SPONGES. 



state, and owing to the fragile manner in which the spicules are held together in 

 the existing species, their preservation as fossils in their normal positions can 

 hardly be expected. Detached spicules closely resembling in form those of existing 

 examples of the genus, but for the most part of larger proportions, are, however, 

 of not infrequent occurrence in Carboniferous and newer strata, and they may 

 provisionally be ranged in this genus. 



I have followed Vosmaer in regarding 0. Schmidt as the author of the genus, 

 since he not only modified Nardo's original name, but was the first to define the 

 characters of the Sponges assigned to the genus. 



19. Rbniera Carteri, Einde. Plate IV, figs. 5, 5 a — 5/. 



1879. Spicule of a Benierid Sponge, Carter. Ann. and Mag. Nat. Hist., ser. 5, 



vol. iii, p. 144, pi. xxi, fig. 11. 

 1883. Eeniera ? Caetebi, Hinde. Cat. Fosa. Sponges, p. 19, pi. i, fig. 8. 



The detached spicules on which this species is based are smooth, cylindrical, 

 gently arcuate, or with a nearly straight central portion and somewhat abruptly 

 incurved extremities, which in all cases are obtusely rounded. They range from 

 '8 to 2'5 mm. in length and from *11 to "22 mm. in thickness. There are numerous 

 gradations between the extreme forms, which indicate that they probably all belong 

 to a single species. 



The spicules are now composed nearly entirely of chalcedonic silica ; in a few 

 instances the silica is crystalline. They are now usually solid throughout, in only 

 a single example of those which have come under my notice has the axial canal been 

 preserved. They are fairly abundant and well preserved. 



Distribution. — Lower Carboniferous : Upper Limestone series at Glencart, 

 Dairy, Ayrshire. 



20. Reniera scitdla, Hinde, sp. nov. Plate IV, fig. 4. 



1880. Renieea ? Carter. Ann. and Mag. Nat. Hist., ser. 5, vol. vi, p. 212, pi. xiv, 

 fig. 14. 



The spicules included in this species are cylindrical, smooth, gently arcuate, 

 and with evenly rounded extremities. They vary from *5 mm. to *9 mm. in length, 

 and from *09 mm. to *15 mm. in thickness. They are now partly of chalcedonic and 



