498 P. EF. Kendall—Aragonite Shells in the Coralline Crag. 
are referable to Mr. Sorby’s calcite division, while the casts without 
any exception are of aragonite organisms. 
SHELLS, ete. Casts. 
Truncatulina (?) Pectunculus glycumeris. 
Polymorphina. Cyprina Islandica. 
Serpula, sp. Cardium, sp. 
Polyzoa (about 89 sp.) Mactra (subtruncata ?). 
Lerebratula grandis. 
Lingula Dumortieri. 
Thracia (2). 
Panopea Fawasir. 
Anomia patelliformis. Tellina, sp. 
Ostrea edulis. ‘Astarte Omalii. 
Pecien Gerardi. Soh SDs 
»> pusio. Nucula nucleus. 
»» maximus. Venus imbricata. 
»» opercularis. . Cytherea chione (?). 
tigrinus. Solen (ensis 2). 
Lima exilis. Teredo. 
», Loscombii. Emarginula fissura. 
Pinna (fragments). Turritella incrassata. 
Scalaria subulata. Trochus, sp. 
Echinus (Woodwardii ?). Nassa (granulata ?). 
Temnechinus, sp. yas pe 
Balanus, sp. Natica, sp. 
Crab claws. Buccinum Daler. 
Cassidaria bicatenata. 
Voluta Lamberti. 
Calyptrea chinensis. 
Some of the casts are of a very remarkable character, the cavity 
being lined with delicate encrusting Polyzoa which had grown upon 
the shell. The backs of the cells would alone be seen of course. 
Serpule occur in a similar manner. 
This case appears to confirm in a striking way Mr. Sorby’s con- 
clusions, for we see that intermingled with casts of the largest and 
most massive of the Crag shells (Voluta, Cassidaria, Panopea, and 
Cyprina) are the most fragile tests (Foraminifera and Polyzoa) in an 
exquisite state of preservation. 
The Scalaria, which constitutes the solitary apparent exception to 
the rule that only calcite organisms are preserved, is I believe really 
a calcite shell for the following reasons :—AlIl the undoubted calcite 
shells of the Coralline Crag are characterized by a very compact 
texture and by being translucent, which characters are common to 
the genus Scalaria, while the aragonite shells have a chalky appear- 
ance and are opaque. 
I believe that this will be found to be a character sufficiently con- 
stant to be of use in determining the zoological position of obscure 
forms, e.g. in the Red Crag of Walton Naze, certain tubular 
tests are found which might be referred either to one of the genera 
of tube-forming Annelids, or to such Gasteropodous genera as Caecum 
or Dentalium. a have however, referred it to the Annelida, because its 
exture is that characterizing calcite shells. 
Mr. Searles V. Wood, in his work on the Crag Mollusca, remarks 
in speaking of the genus Vermetus, “This approaches so near to the 
testaceous Annelides that it cannot be distinguished by the shell 
alone ;” but I conceive that in the Pliocene fossil examples at least 
