245 
The elegant markings with which the flat surfaces of these bodies are 
adorned are, like those on the surfaces of the trochitje, calculated to 
form an appropriate articulation with the surfaces of other similar 
bodies. By the union thus obtained are formed those pentagonal 
columnar bodies, which are generally known as columnar star-stones, 
or Asteria Columnares, and by some as angular stellated entrochi, (En- 
trochi Angulares Stellati). 
These columns derive a considerable degree of variety, from the 
difference, in structure and size, of the asteriee of which they are 
composed, as well as from the order in which they are arranged : their 
external markings, therefore, differ considerably. These differences have 
been very accurately described by Rosinus, and shall be here noticed, as 
closely as appears to be necessary. 
In some, as in Fig. 52, the constituting asterise are of a similar 
size and form : the line of articulation is therefore at the same dis- 
tances through the whole column. See Rosinus also. Tab. IV. B. 1. 
But in those columns which are formed of asteriee of different thick- 
nesses, a correspondent difference in the distances will be observable 
in the lines of articulation, since these will be more or less frequent, 
as the asteriae are thinner or thicker : their lines of articulation w ill 
also be more or less undulating, as the asterite are more or less grooved 
on their sides. 
Fig. 48 and 53 consist of thicker and of thinner columns of asteriae, 
alternately disposed. Fig. 49 is formed by the thicker asteriae so 
ranging with those which are thinner, and with those which are of the 
thinnest kind, that between two of the thicker are placed two of the 
thinnest, between which is placed one of a medium thickness. Rosinus 
describes several varieties of this species, depending merely on the diffe- 
rent degrees of thickness in the thinnest asteriae, and in the degrees of 
fineness in the crenulated markings in the line of articulation. 
Fig. 51 represents a columnar series of round asteriae, and composed 
of thick, less thick, of thin and of the thinnest asteriae, so disposed. 
