26 
Mr. H. J. Carter on the Microscopic 
Solenodon also confirm my determination of the homologies in 
Centetes*. 
In conclusion I give the following synoptic view of the 
constitution of the superior molar teeth in various genera of 
the Bunotheria. 
CUSPS PRESENT. 
External, 
intermediate, 
two internal. 
Adapidie. 
|Tupeeidee. 
\Galeopithecide. 
Soricidie. 
Urotrichus. 
| 
| 
| 
External, 
no intermediate, 
two internal. 
Gymunura. 
Erinaceus. 
Macroscelidide. 
External, 
intermediate, 
one internal. | 
Mystomyidee. | 
Mioclezenus. 
Miacis. 
Talpidee. 
\(Didelphys.) 
(Canis.) 
\Oxyeena. 
(Chriacus. 
‘Deltatherium. 
|Esthonyx. 
External, 
no interme- 
diate, 
one internal, 
Mesonyx. 
Leptictis. 
Stypolophus. 
(2nd internal 
rudimentary ). 
No external, 
no inter- 
mediate, 
two internal. 
Chrysochloris 
(2nd internal 
rudimentary). 
Solenodon 
(ditto). 
No external 
no interme- 
diate, 
one internal 
Centetes. 
I1l.—On the Microscopic Structure of thin Slices of Fossil 
Calcispongie. 
By H. J. Carter, F.R.S. &e. 
In the “ P.S.” which I hastily added to my last “ Observa- 
tions on the so-called ‘ Farringdon Sponges’ (Calcispongie, 
Zittel),” it is stated that Dr. Harvey B. Holl had kindly sent 
me four slides, testifying respectively to two facts, viz. 1st, 
that the spiculation of Verticillites anastomans was that of a 
Calcisponge, to me 
size”? with that of Grantia compressa; and 2nd, that it was 
confronted by a crust of pinlike spicules with their heads 
outwards; and at the conclusion, that I had no¢ seen the latter 
in my specimens of Vertdicillites anastomans from Farringdon 
in Berkshire. 
Wishing to confirm this, I obtained through Dr. Holl’s 
kindness his entire specimen, and having made two or three 
6c 
precisely like and almost identical in 
* This view was first advanced by the writer in the Annual Report 
U.S. Geol. Sury. Terrs. 1873-74, p. 472. 
