PLATE XXXII. 



Page 

 Figs. 1-1 g. Hyalostelia Smithii, Young and Young, sp. Detached spicules of this species. 



Enlarged fourteen times. Figs. 1 to 1 o? are simple hexaetinellid forms ; in 1 



and 1 c one of the spicular rays is reduced to a rounded knob ; figs. 1 e, 1/, and 



1 ff are terminal portions of the spicular rods with four recurved rays. From 



Lower Carboniferous Limestone at Cunningham Baidland, near Dairy, Ayrshire 150 



Figs. 2-2/. Holasterella conferta, Carter. Detached spicules of the species. Enlarged 

 fourteen times. Figs. 2 to 2 c are the simpler forms ; fig. 2 f? is an imperfect 

 stellate spicule ; 2 e is the upper surface of one of the petal-like spicules, and 

 2/ is the under surface of a similar but larger spicule. These various forms 

 have been found in combination in fragments of the sponge. From Lower 

 Carboniferous Limestone, Law Quarry, Dairy, Ayi'shire 152 



Figs. 3-3 d. Holasterella Youngi, Hinde. Detached umbrella-shaped spicules. Enlarged 

 fourteen times. Fig. 3 shows the U2)per surface of a spicule which is smooth ; 

 in 3 a, 3 6 the vertical rays of the spicule are seen, and the upper surface is tuber- 

 culated ; 3 c shows the under surface and the vertical ray of a small spicule ; 

 and 3 d is the upper surface of a large spicule in which the rays are nearly in a 

 horizontal phiue. From Lower Carboniferous Limestone at Law Quarry, near 

 Dairy, Ayrshire 152 



Figs. 4-1^. Holasterella Wrightii, Carter. Detached spicules of the species. Enlarged 

 twenty-eight times. Figs. 4, 4 c, 4 6 are imperfect hexaetinellid spicules with 

 simple rays ; 4 c, 4 f/ are fragments of hexaetinellid spicules with bifurcated 

 rays ; 4e, 4/ are hexaetinellid spicules in which the rays are subdivided so as to 

 give the appearance of stellates; and 4^ is the terminal portion of a spicular 

 rod with four recurved I'ays, which may have formed part of the root-appendages 

 of the sponge. From Lower Carboniferous Chert, Ben Bulbul, Sligo, Ireland . 153 



Figs. 5-5 e. Holasterella Benniei, Hinde. Detached spicules of the species. Enlarged 

 fourteen times. Figs. 5 to 5 c are hexaetinellid forms with the rays variously 

 subdivided ; 5 e is a five-rayed form with the rays simple ; and 5 t? is also five- 

 rayed, and the rays bifurcate near their extremities. From Lower Carboniferous 

 Limestone, Law Quarry, Dairy, Ayrshire 153 



Fig. 6. Peronella inflata, Hinde. Natural size. From the Middle Jura — Couche a Poly- 

 piers : Ranville, near Caen 1G7 



Fig. 6 a. The same. Portion of the fibre in the marginal part of the stem, enlarged seventy- 

 two times, showing traces of three-rayed spicules. Drawn from a transparent 

 microscopic section by means of the camera lucida. 



Fig. 6 b. The same. Showing the spicular structure in the interior portion of the stem. 

 Enlarged seventy-two times. 



