152 BRITISH PALAOZOIC SPONGES. 
occurs, it has a conical head and simple rays directed backwards; the shaft is 
imperfect. This anchor is intermingled with acerate spicules similar to those 
occurring with the zone-spicule. 
With the same forms of acerate spicules at Richmond, there are present one or 
two examples of kidney-shaped spicules similar to those of the dermal layer of the 
existing Geodia. They vary from *13 to ‘2 mm. in diameter. It is very doubtful 
if these really belong to the same Sponge as the zone, anchor, and acerate spicules, 
and they are but provisionally placed with them. These dermal spicules have not 
previously been found so low as the Carboniferous Rocks. 
Distribution.—Yoredale series: Henblas, Trelogan, Flintshire; Richmond, 
Yorkshire. 
34, GuopitEes simpLEx, Hinde, sp. nov. Plate IV, fig. 3. 
1880. ACcCERATE SPICULE OF UNKNOWN Sponae, Oarter. Ann. and Mag. Nat. Hist., 
ser. 5, vol. vi, p. 212, 
pl. xiv, fig. 15. 
Straight or curved acerate fusiform spicules, gradually tapering from the centre 
to acutely pointed extremities. They vary from °55 to 1:4 mm. in length, and 
about ‘1 mm. in thickness. No trifid or zone-spicules have as yet been found in 
the same beds with these acerates ; but, judging by their form and proportions, it 
seems probable that they belong to a Sponge of this genus, and they are provision- 
ally included in it for convenience of reference. Some of the forms were obtained 
by Mr. J. Wright from decayed chert, whilst others were found in a small hollow 
in a block of chert. 
Distribution—Carboniferous ; Upper Limestone series, Ben Bulben, Sligo. 
Yoredale (?) series, Gwydfyd, Great Orme’s Head, North Wales. 
Genus—PacHastrELLA, O. Schmidt. 
1868. Die Spongien der Kiiste von Algier, p. 15. 
Syn.—Battersbya, Bowerbank ; Dercitus, Gray. 
Generic Characters.—Massive, nodose, platter-shaped, or irregularly expanded 
Sponges, without specialised dermal layer, frequently attached to and incrusting 
other Sponges. No special canals shown in fossil examples. The skeleton consists 
