Pip peclile: é : ) 
Lp fpa (fk. jif= fA. KW HK), PY- 
fat UL,, / 7) Ye / JA: JL f~- 80. F* Z “1 XY 
PULMONATA. 121 
extremities, and although they are generally regular in form, as I have already stated | 
yet specimens occasionally occur more nearly spherical. The substance forming these 
casts is most frequently close and compact, like the rock in which they are embedded ; 
sometimes, although rarely, the cavity is partially filled with matter, apparently the 
same as the matrix, but more granular, and sometimes crystalline, as if due to 
percolation. 
I am aware that by some these substances are regarded as coprolitic ;* that by 
others they are considered to be the remains of seed vessels ; and, again, that by others 
their origin is attributed to the coccoons of insects ; and I am desirous that the opinion 
I have expressed should be received as a suggestion, rather than as an induction from evi- 
dence which, it must be admitted, is inconclusive. As bearing, however, on the subject, 
and, if not supporting the view I have taken, at least presenting in some respects an 
analogy with the substances in question, I may refer to the instance of the eggs of 
turtles found on the shore of the Isle of Ascension, embedded in a recent limestone 
formed of sand, comminuted shells, and corals agglutinated together.{ A small mass 
of this rock, enclosing several eggs, is in the Museum of the Geological Society of 
London; the cavities of the eggs are filled with the material forming the matrix, and, 
although the calcareous shell remains, we have only to imagine the eggs embedded 
under circumstances which would cause the dissolution and absorption of the cal- 
careous matter, and some of the very conditions in which the substances in question 
are found would be exactly represented. 
A series of these substances, showing the different sizes and forms, is represented 
by the woodcuts in the next page. Those most commonly found are represented by figs. 
2,3, 4, and 5; they present a close resemblance, both in size and shape, to the 
eggs of several of the recent fresh-water tortoises, and may be casts of eggs of some of 
the species of Zonya or Hmys, which lived in the Eocene rivers or marshes. Those 
represented by figs 8, 9, and 10, may be casts of some of the Helicide. 
* With regard to the suggestion that these substances are coprolitic, it must be stated that the casts, 
some of which have been subjected by Mr. Morris to chemical analysis, do not present any trace of phosphate 
of lime ; the presumption, therefore, is against their being coprolites of a carnivorous animal, and the constant 
regularity of their form, and the absence of carbonaceous matter, militate as strongly against the idea that 
they are fecal remains of an herbivorous animal. 
+ Lyell’s ‘ Principles of Geology,’ 9th edit., p. 77. Ansted’s ‘Geology,’ vol. ii, p. 137. 
16 
