Ascoclictyon and Rhopalonaria. 



79 



__opaque objects on shell-fragments they appear like fine hairs 

 laid in lines across the surface, or contorted, crossing- each 

 other at different angles, or running in parallel lines ; but it 

 would be useless to direct attention to any special feature in 

 their modes of growth, for they vary considerably ; but one 



Fig'. I. 



1. ^5co^«rfyo??^fo/orm<', Viue, y|-o inch thick. Two filiform threads run- 



ning almost parallel. The point of origination is a^ ; the portion 

 marked a is nearly similar, but wanting the nucleus ; «'- single 

 vesicle. 



2. A. radiciforme, Vine, -fig inch thick. One of the filiform contracted 



threads, placed here for comparison. 



3. Thread of A.filiforme, drawn from a transparent specimen, showing 



dark brown pulp. 



feature which appears to me to have something to do with the 

 development of the colony must not be lost sight of. Occa- 

 sionally some of the filaments bifurcate, and before bifurcation 

 takes place the organism contracts at intervals, and out of this 

 contracted portion a new thread originates. It must not be 

 supposed, however, that this simple explanation is, on the 

 whole, a plainly satisfactory one. The two different sorts of 

 threads, though apparently allied, give rise to two distinctly 

 separable colonial growths in the after stages of their exis- 

 tence. Yet in the earliest, or initial stages, it is not easy 

 to distinguish the difference between tliem. It will be better, 

 however, to keep the two forms distinct. 



In a few cases I have been able to reduce the thickness of 

 the shell to which a typical A. Jiliforme is attached, and have 

 mounted the specimen in balsam on glass. It is then seen 

 that the filament is hollow, and the central parts filled with a 

 dark brown granular matter. This granular matter, which I 



7* 



