DR. G. J. HINDE ON RECEPTACULITIDA. 803 
hardly doubtful. As regards Zetragonis, the author remarks that 
our knowledge of it is as incomplete as its position is uncertain, and 
that the presence of surface-plates has not been decisively deter- 
mined any more than the existence of perforations at the angles of 
the squares into which the surface of the fossil is divided as de- 
scribed by Hichwald. In addition to the type species 7’. Murchisoni, 
Eichw., the author includes in Tetragonis, T. Danbyi, McCoy, and 7. 
eifelrensis, ROm., which, however, do not properly belong to the genus. 
As the essential characters of the other genera placed by Romer in 
the Receptaculitide, namely Cyclocrinus, Eichw., Pasceolus, Bill., 
and Archeocyathus, Bill., do not in my opinion agree in the least 
with those of Receptaculites and its allied genera, it is not worth 
while to notice his statements respecting them. | 
In the first part of the first volume of the ‘ Handbuch der Pala- 
_ ontologie’ (1876), p. 83, Prof. Zittel places Receptaculites in the 
family of the Dactyloporide ; but in a supplement at the end of the 
volume (p. 727) Leceptaculites and its allied genera are stated to 
form an altogether doubtful group ; and as they have hardly a single 
typical feature in common with Foraminifera, and as the Dactylopo- 
ride, with which they were placed by Gumbel, are now known to 
be calcareous Alge, and not Foraminifera, they should be removed 
from this Order. In addition to the various genera included in this 
family by Romer, Zittel further adds Goniolina, D’Orb., Archeo- 
cyathellus, Ford, and Protocyathus, Ford. 
Lastly, in the ‘Catalogue of the Fossil Foraminifera in the British 
Museum’ (1882), Prof.'T. Rupert Jones gives a list of the species of 
Receptaculites and its allies under the heading of ‘“ Rhizopoda of 
uncertain alliance.” In a note on the Receptaculitide (p. 83) the 
author adopts Gumbel’s reference of the leading genus to Foramini- 
fera on the ground of the similarity of its structure to Dactylopora. 
Terminology employed. 
In conformity with the opinion which I shall endeavour to esta- 
blish, that the systematic position of the Receptaculitide is with 
Sponges, it seems desirable to employ other terms for the component 
parts of the organism than those which have been used by Gtimbel, 
Dames, and other writers, who have regarded these organisms as 
Foraminifera. I propose therefore to adopt the term “ spicules ” 
for the component parts of these fossils. The different parts of each 
separate spicule may be designated as follows:—(1) ‘‘ Head- or 
summit-plate” of the spicule, for the rhomboidal or hexagonal-plates 
of the outer surface, which are the equivalents of the rhomboidal- 
plates of the ectorhin, Billings ; rhomboidische Tafeln, Dames ; rhom- 
bische Plattchen, Gumbel. (2) For the four horizontally extended 
arms or rays immediately beneath the head-plate (the Stolons, Bill. ; 
Kanile, Dames ; Epistyle, Stutzarme, Giimb.), I propose the term 
‘horizontal rays” of the spicule. (3) For the tapering or subcylin- 
drical arm or ray extending at right angles to the horizontal rays 
towards the interior of the organism, and in Receptaculites reaching 
to the inner plate (the cylindrical tubes or hollow spicula, Bill. ; 
