148 BRITISH PALEOZOIC SPONGES. 



washing his specimen, and which were supposed to have been incorporated in its 

 fibres, were most probably derived from the debris infilling the interspaces between 

 the fibres, and did not form part of the fibres themselves. In Dr. Hunter's type 

 specimen of H. Armstrongi, the interspaces between the fibres were similarly filled 

 with spicules and other debris ; but in none of the specimens which have come 

 under my notice is there any structural connection between these extraneous 

 spicules and the fibres. 



At the time of describing Haplistion fractum I had not seen an authentic 

 specimen of H. Armstrongi, but a comparison with those forwarded to me by Dr. 

 Hunter and Mr. J. Smith leaves no doubt that the fragments I named belong to 

 Messrs. Young's species. 



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

 ningham Baidland, Law Quarry, Dairy, Ayrshire. 



29. Haplistion veemiculatum, Garter sp. Plate V, figs. 2, 2 a. 



1878. Ehaphidhistia vermiculata, Carter. Ann. and Mag. Nat. Hist., ser. 5, 



vol. i, p. 140, pi. ix, figs. 15 — 19. 

 1883. — — Hinde. Cat. Foss. Sponges, p. 208. 



Small, depressed convex, or irregularly rounded Sponges, apparently free. 

 The type-specimen is 12 mm. in width. The fibres either anastomose irregularly, 

 or in some specimens are vertical with transverse connections. At the surface 

 they terminate in blunt conical processes. The fibres vary from "67 to "9 mm. in 

 thickness. As in the preceding species they are solid, and are composed of 

 straight and slightly curved spicules, which are interlaced with each other. A 

 fairly long spicule measures "3 mm. 



The typical specimen described and figured by Mr. Carter, now in the collection 

 of Mr. J. Thomson, who kindly forwarded it to me for examination, is depressed 

 convex, with a flattened basal portion, which appears to me to be, in part at least, 

 a fractured surface, but which Mr. Carter regards as a continuous membranous 

 attachment, now lapidified. Mr. Carter further described the fibres as belonging 

 probably to a fossil example of Hydr -actinia on which the Sponge was parasitic. 

 It seems to me, however, more probable that, as in H. Armstrongi, the fibres of 

 this species were throughout composed of interlacing acerate, siliceous spicules, 

 which are now, with the exception of those weathered out on the surface, indis- 

 tinguishably fused together. I do not think the fibres were originally hollow as 

 stated by Mr. Carter ; the cavities in them appear to result from erosion. The 

 spicules in the type-specimen, as well as in others sent to me by Mr. J. Smith, 



