506 
Agassiz, of the second part of his description of the fossil Echino- 
dermata of Switzerland*. 
The family of Cidarides forms the exclusive subject of this me- 
moir, being the most numerous of all the families of Echinites, and 
at the same time the earliest form under which shells of this kind 
appear to have existed; they are the only family that occurs so 
early as the muschelkalk, whilst no other family of Echini is found in 
formations older than the Jurassic, in which the Cidarides are most 
numerous; they abound also in the cretaceous and tertiary formations, 
and in our actual seas+. In the Jura mountains they are most nu- 
merous in a stratum, called Yerrain a Chailles, abounding, with 
other littoral shells, near the middle region of the oolite formation. 
Professor Agassiz has also published the first monograph of an- 
other splendid work, ‘ Monographies d’Echinodermes, vivans et fos- 
siles, which will be extended to ten or twelve parts, to be completed 
in three or four years, and will contain about 150 plates, some of 
them coloured, from careful drawings of this most beautiful class 
of shells. Collections of casts of all the fossil species of this class 
known to M. Agassiz may be obtained by purchase, or in exchange 
for objects of natural history, at the Museum of Neufchatel. 
In the family of Star-fish two new fossil genera have been recently 
established by Mr. Gray{, one of these, Comptonia, founded on a 
specimen from the whetstone pits in the greensand of Blackdown, 
Devon, recently acquired by the Marquis of Northampton ; it is 
preserved in the state of beautiful chalcedony, and explains the in- 
termediate character of the genus Ceelaster of Agassiz. The other 
new genus Fromia, comprehends the curious tesselated star-fishes 
found in the chalk, and also a recent species found i in various parts 
of New Holland. 
Professor Agassiz will shortly send an artist to England, to figure 
for his great “eile on living and fossil Behinadeniee the individual 
specimens which Mr. Gray has described in his Monograph on Star- 
fish. It is a new and important feature in the progress of zoology 
and palzontology, that this much-neglected department of radiated » 
animals is at length receiving that attention which, from the time of 
Henry Linck, who dedicated a large volume on this subject to Sir 
Hans Sloane (1738), to the moment when it has recently been re- 
sumed by Nardo, Agassiz, and Gray, it has so long merited in vain. 
SPONGES IN CHALK FLINTS. 
‘Mr. Bowerbank, in a paper on siliceous bodies in the chalk, green- 
sand, and Portland oolite, has applied the evidence of microscopic 
* Mémoires Nouveaux de la Société Helvétique des Sciences Naturelles, 
vol. iv. 
+ Cidarides have recently been found in the carboniferous limestone of 
the Mendip Hills, near Frome, by Miss Bennet, and by myself in the car- 
Donn eTeus limestone near Donegal, in 1811. 
{ See Monograph on Star-fish, Ann. Nat. Hist., No. 36, Nov. 1840, 
p. 175. 
