THE society's NOTE-BOOKS. 389 



Spongilla fluviatilis.— No. 4 is a section of a fresh-water sponge 

 {S. fluviati/is). This specimen is hterally filled with statoblasts or 

 winter germs ; these are seen to be built up with spiculae of a dif- 

 ferent make from those of the mass — bi-rotate — with eight or ten 

 points. 



The four following slides are from the family of the Adinice, the 

 Sea Anemones. This group of animals consist, in their simpler 

 forms, of a gelatinous sac, unsupported by spiculae, with a cavity 

 which acts as a stomach, and of which the orifice is surrounded by 

 a row, or rows, of tentacles. In some species the soft matter of 

 the animal, as in the SerlularicB, is supported by a horny pol3'^pi- 

 dom ; in others, as the Alcyonium, the soft matter is stiffened by 

 numerous short, calcareous spiculae ; while in others, as the Corals, 

 the polyps secrete a skeleton of calcareous plates, within the 

 limits of which it can withdraw itself when disturbed. Our speci- 

 mens are confined to the first and third of these groups. 



Adamsia rondoletta. -No. 5 is a section o{ Adamsia ro7idoletta. 

 The Adamsia are sea anemones that are almost always found 

 adherent to the vacant shells of certain molluscs ; they affix them- 

 selves round the orifice of these shells, whence they are called 

 " Cloak anemones," and the shell is very often found to be also 

 tenanted by a hermit crab. 



On No. 6 are sections of the anterior and posterior parts of 

 Peachia hastata, an anemone which buries itself in the sand, having 

 the power, at will, of protruding the anterior part through the sand 

 and displaying its row of tentacles. 



Alcyonium dig^itatum.— No. 7 comprises sections of Alcyonium 

 digitatum (Dead Men's Fingers), one of the composite ActifiicE 

 that secretes calcareous spicules, which in the specimen are seen in 

 situ. It will be noticed that they are closely aggregated towards 

 the exterior of the animal, giving it solidity and firmness. The 

 section also shows the polyps occupying cells near the exterior of 

 the composite animal. 



No. 8 is one of the polyps of Alcyonium digitatum detached 

 from the mass, in order to show its analogy with a simple actinia. 



The remainder of the slides are preparations from the class of 

 animals of which the ordinary Star-fish (Cross-fish) is the type. 



