176 REPORT—1843. 
series of sedimentary depositions, the evidences of its fauna which would be 
presented may be summed up as follows :— 
1. Of the higher animals, the marine Vertebrata, the remains would be 
scanty and widely scattered. 
2. Of the highest tribe of Mollusea, the Cephalopoda, which though poor 
in species is rich in individuals, there would be but few traces, saving of the 
Sepia, the shell of which would be found in the sandy strata forming parts 
of the coast lines of the elevated sea-bed, 
3. Of the Nudibranchous Mollusca there would not, in all probability, be 
a trace to assure us of their having been; and thus, though we have every 
reason to suppose from analogy that those beautiful and highly character- 
istic animals lived in the tertiary periods of the earth’s history, if not in older 
ages, as well as now, there is not the slightest remain to tell of their former 
existence. 
4. Of the Pteropoda and Nucleobranchiata the shell-less tribes would be 
equally lost with the Nudibranchia, whilst of the shelled species we should 
find their remains in immense quantity characteristic of the soft chalky deposits 
derived from the lowest of our regions of depth. 
5. The Brachiopoda we should find in deeply-buried beds of nullipore and 
gravel, and from their abundance we could at once predict the depth in which 
those beds were formed. 
6. The Lamellibranchiate Mollusca we should find most abundant in the 
soft clays and muds, in such deposits generally presenting both valves in their 
natural position, whilst such species as live on gravelly and open bottoms 
would be found mostly in the state of single valves. 
7. The testaceous Gasteropoda would be found in all formations, but more 
abundant in gravelly than in muddy deposits. In any inferences we might 
wish to draw regarding the northern or southern character of the fauna, or 
on the climate under which it existed, whether from univalves or bivalves, 
our conclusions would vary according to the depth in which the particular 
stratum examined was found, and on the class of Mollusca which prevailed 
in the locality explored. 
8. The Chitons would be found only in the state of single valves, and pro- 
bably but rarely, for such species as are abundant, living among disjointed 
masses of rock and rolled pebbles, which would afterwards go to form con- 
glomerate, would in all probability be destroyed, as would also be the case 
with the greater number of sublittoral Mollusca. 
9. The Mollusca tunicata would disappear altogether, though now form- 
ing an important link between the Mediterranean and more northern seas. 
10. Of the Arachnodermatous Radiata there would not be found a trace, 
unless the membranous skeleton of the Veled/a should under some peculiarly 
favourable circumstances be preserved in sand. 
11. Of the Echinodermata certain species of Achinus would be found en- 
tire; species of Cidaris, on account of the depth at which that animal lives, 
would be not unfrequent, in certain strata, as the region in which it is found 
bounds the great lowermost region of chalky mud ; the spines would be found 
occasionally in that deposit, far removed from the bodies to which they be- 
longed. Starfishes, saving such as live on mud or sand, would be only evi- 
denced by the occasional preservation of their ossicula. Of the extent of 
their distribution and number of species no correct idea could be formed. 
Of the numerous Holothuriade and Sipunculide it is to be feared there 
would be no traces. The single Crinoidal animal would be rarely preserved 
entire, but its ossicula and cup-like base would be found in the more shelly 
deposits, 
