JOINTS. 55 



calcareous iuternodes are united by a bundle of about 20 

 noncalcified tubes forming the node. The calcareous matter 

 is most dense at the external surface of the internode. 

 From the shores of the Mediterranean and West Indies. 

 PI. IX. fig. 2. Presented ly G. R. M. Murray, Esq. 



B. 40. A calcareous Alga, one of the Floridese (Amphiroa 

 epheffrceci), and drawing of its structure. The flexible nodes 

 consist of noncalcified cells. In the internodes the cell- 

 walls are calcified, stiff and brittle. When fresh or moist 

 the plant readily bends without breaking, but when dry the 

 slightest touch causes fracture. From the Cape of G. Hope 

 and Australia. PI. X. fig. 1. 



Presented by G. R. M. Murray, Esq. 



ANIMALS. 



B. 41. Zoarium of a Bryozoan (Crisia eburnea), and drawing of 

 its structure. The tubular polyp -chambers (zooecia) have 

 rigid and brittle calcareous walls. The first zocecium of 

 each branch has a horny ring within the calcareous walls 

 that are here partly interrupted so as to expose the ring and 

 allow of flexion. This part constitutes the node. The 

 radical tubes by which the animal is attached have many 

 such nodes. PI. X. fig. 2, 



B. 42. Zoarium of another Bryozoan (Cellaria sittuosa), and 

 drawings. The branching is dichotomous. Each branch 

 normally commences by 8 special zorecia having their 

 interior lined by flexible horny matter. The calcareous 

 walls break at this point, exposing the dark horny material 

 as a flexible bond of union forming the node. These con- 

 necting zoo3cia are devoid of the polypide present in all the 

 others, they also differ in other respects. PI. XI. fig. 1. 



B. 43. Cellaria ninuosa. Being preserved in spirit the black 

 horny material of the nodes is more distinct, as it can be 

 seen through the calcareous walls of the zorecia. 



B 44. Small portion of a Bryozoan (Membranipom membranacea) 

 iucrusting a Seaweed (Laminaria saccharina), with drawing 

 of structure, The seaweed is constantly beiidiiig in the 



