182 K.OLL1KER, ON VEGETABLE PARASITES. 



straight and tolerably regularly disposed tubuli, which agreed 

 in all essential points with those of the shells above noticed, 

 but exhibited neither branches nor sporangia, and conse- 

 quently could not be so definitely referred to a fungus- 

 mycelium. But if "Wedl's observations are taken into account, 

 it may be confidently stated that this is the only correct in- 

 terpretation they admit of. 



(e) Thracia distorta 



Contained a good many fine fungus-filaments, with numer- 

 ous ramifications. Close to many of the filaments were 

 large, round, finely granular bodies, which are probably 

 sporangia. 



(/) Astrea edulis. 



In a shell much excavated by Clione, the portions yet 

 retaining their integrity were pervaded by a greater abund- 

 ance of fungus-filaments than I have as yet observed else- 

 where. The filaments were rather closely branched, and 

 occasionally presented terminal enlargements, which could 

 perhaps be regarded only as sporangia. 



(g) Meleagrina margaritifera. 



A beautiful vertical section of this shell was particularly 

 interesting, from the circumstance of its showing that shells 

 with a perfect prismatic layer might also contain parasites. 

 These were most developed in the outermost layers of the 

 prismatic stratum, but in many instances through its 

 entire thickness, and beyond it to a greater or less depth into 

 the nacreous layer. The filaments were some 0*002 

 and O^OOS'", some finer, and no sporangia were visible upon 

 them. 



Many other bivalve shells presented no trace of parasites. 

 Among which may be enumerated — Pinna ingens, Pinna 

 nigrina, My a arenaria, Unio occidens, the prismatic layer of 

 Perna ephippium, Avicula, Crenatula, Malleus albus. 



5. Beachiopoda. 



The shells of certain Terebratuhe, besides the well-known 

 coarser tubes, are also penetrated by extremely minute canali- 

 euli, which, in respect to appearance and diameter, closely 

 resemble the tnbuli of dentine, and can scarcely be regarded 

 except as fungus-filaments. 



They were seen in Kraussiu rubra, Tercbratiilu Australia, 

 and T. rubicunda, for sections of which I am indebted to Dr. 



