Structure of Fossil Calcispongic. 27 
slides from it, found in all what I have stated; while, seeing 
that the specimen was identical with one of my own from Far- 
ringdon, I did the same with this with the same result; but 
when thus engaged I saw that I had specimens of another 
form in my collection, and that this also presented the pinlike 
spicules. It was then evident that there were two, viz. Dr. 
Holl’s and another, and that they chiefly differed in the form 
of the siphonal cloaca which passes through the centre of each 
septum, like that of an Orthoceras, only with the convexity of 
the septa reversed (that is, directed upwards or outwards) in 
Verticillites. In Dr. Holl’s specimen this passage is reduced 
toa marginated circular hole of intercommunication in the septa 
which separate the chambers; while in the other form it is 
a continuous tube or cylinder communicating with the chambers 
respectively by holes in its s¢des, which thus, through this 
canal, establish a communication with the exterior. 
On reference to Dr. Gustav Steinmann’s figures (“* Pharetro- 
nen-Studien,’’ Neues Jahrbuch f. Mineral. Geol. u. Palionto- 
logie, 1882, 11. Bd. Taf. vi. u. vii. figs. 5,6 u. 1 respectively) 
I see that Dr. Holl’s species has been called “ helvetica”’ by 
De Loriol (Urgonien infér. de Landeron, p. 65, t. v. figs. 4— 
11); while the other form had long since received the name 
of “ Verticillipora (Verticillites, Detr.) anastomans” from Man- 
tell (‘ Wonders of Geology,’ p. 636, fig. 3, &c.). 
The pinlike spicules, however, are present in doth, and ar- 
ranged in the manner of a funnel, with the spout inwards or 
continuous with each external aperture of the radial canals, as 
may be proved by making a horizontal and vertical section of 
the wall respectively, when the full length of the pinlike 
spicules is seen in the former sloping inwards towards the 
canal, and their truncated ends in a circle surrounded by the 
triradiates in the latter, while by making one horizontally 
through the septum and the wall together both may be seen 
at once. ‘The pin spicules, like the triradiates, are dissolved 
by diluted nitric acid, although generally preserved in form 
when that of the triradiates has almost entirely disappeared. 
It is very probable that Dr. Holl’s specimen came trom the 
same neighbourhood as my own; but, be this as it may, it 
would be desirable to ascertain if the pinlike spicules are 
absent in the species from the Jura and elsewhere out of Eng- 
land, as they are in Dr. Hinde’s Verticillites D’ Orbignyi, 
which came from the Upper Greensand at Warminster in 
Wiltshire, within twenty-four miles of Farringdon. 
The next point to which I would direct attention is the 
change which takes place in the spiculation of the Calcispongiz 
during fossilization, to which I have also hastily alluded 
