154 BRITISH PALASOZOIC SPONGES. 
36. PacHastRELLA HuMILIS, Hinde. Plate IV, fig. 7. 
1880. QUADRIRADIATE SPICULE, Carter. Ann. and Mag. Nat. Hist., ser. 5, vol. vi, 
p- 212, pl. xiv, fig. 17. 
This name is proposed for detached four-rayed spicules of the normal type- 
The rays are simple, three of them are subequal in the same spicule, whilst the 
fourth or vertical ray is apparently shorter than the others. The rays are about 
‘3mm. in length by ‘07 mm. in thickness. These are more regular in form 
besides being distinctly smaller than those placed under P. vetusta, and they appear 
to indicate a distinct species. They are of rare occurrence in the decayed chert 
of Ben Bulben, and specimens in a fragmentary condition are present in the 
Sponge-beds at Halkin. In both these localities they are siliceous, and in the 
Same mineral condition as the hexactinellid spicules intermingled with them. 
Distribution.—Upper Limestones: Ben Bulben, Shgo (J. Wright). Yoredale 
Series: Henblas, Flintshire. 
Sub-Order.—LitHistipm. 
Family.—Ruizomorina. 
Genuws.—CNEMIDIASTRUM, Zittel. 
1878. Studien iiber fossile Spongien. Zweite Abth. Abhandl. d. k. bayer. Akademie 
der Wissenschaften, Cl. ii, Bd. xiii, Abth. 1, p. 109. 
Syn.—Cnemidium (in part); Achilleum (in part), Goldfuss, Quenstedt ; Cnemi- 
spongia, Quenstedt ; Cupulospongia (in part), D’Orbigny ; Cnemiopelta, Cnemi- 
psechia, Pachypsechia, ? Ceriopelta, Trachycinclis, Pomel. 
Generic Characters.—Sponges for the most part simple, rarely compound, 
conical, cylindrical, turbinate, and vasiform, with thick walls and deep cloacal 
cavity. The walls are traversed by numerous vertical fissures, which towards the 
exterior bifurcate and anastomose with each other. These fissures consist of 
canals placed directly over one another and separated from each other by thin 
partitions of the spicular skeleton. A smooth dermal layer extends over both the 
outer and inner surface of the Sponge-wall, and the canal-apertures either project 
slightly above this layer or are in shallow depressions below it. The skeleton 
consists of moderately large spicules of curved irregular forms, branching at the 
