58 
sulphate. Why the barytes should show a preferential selec- 
ion of these empty annelid chambers, as is assumed in th 
at most minerals in solution show a tendency to undergo 
precipitation on reaching a cavity in the rocks. 
DESCRIPTION OF PLATE IX. 
Pig L ean of vermiform-like object, entwined. Slightly 
under natural siz MORS 
tly, two objects of a similar 
Sis ‘ajacent s ae Ci ihe other. Slightly under 
natural s e 
Fig. Pu Cast of similar object, showing irregular twisting. 
Natural size. 
Fig. 4. Cast in which e coils are more regularly arranged 
in a spiral form. Naturals 
Fig. 5. Another rires in which the coils are wound 
right A ds to each other. The s ecimen is a a fragment showing 
fracture at both e xtremities. Natural siz 
Fig. 6. In this "- cimen the coils are woun nd around a centra al 
ation of the coil is seen at the upper margin. This example poke 
an intermediate type between the worm-like casts on the one 
and the discoidal “buns” on the other. Natural size. : 
Migs. 1, 4, 5, and 6 agree in the diameter of their decem 
coils; and fips. 2 and 3 also agree with each other in this resp 
bei : 
o entionec. 
In the two examples shown in figs. nd 3, slight e ye eee 
occur in the bedy whorls (especially where ‘the latter ma all 
acute Phe “in may have been caused by a succession of dir al 
bulgings of an annulated soft body as the result of longitu pur 
press This feature, while quite distinct in the objects, is 
well eax by the photogr aphs. 
