138 
Professor Kolliker maintains the fungoid nature of these 
tubuli in shells as well as in other hard tissues of animals, 
as fish scales, &c. 
Wedl, another investigator, considers the tubuli in all bi- 
valves as produced by vegetable parasites, and that no other 
interpretation can be given. 
This view does not seem to be borne out by the section 
of another shell which was exhibited, “Area navicula,” in 
which the tubuli are always present, forming an integrant 
part ; they are disposed in a straight and tolerably regular 
manner between the ridges of the shell; moreover, they 
have neither the irregularly branched structure nor the 
sporangia. 
Erratum. — In the last number of the “Proceedings,” 
p. 99, line 9 from top for “ Regnalt” read Renault. 
