NATURAL SCIENCES OF PHILADELPHIA. 16t 



Some are green from the chlorophyl bulls occupying tbe superfi- 

 cial part of the bod3\ Others exactly alike in all other points of 

 structure are colorless. From the body project a multitude of 

 exceedingly delicate spines with discoid bases and furcate ends. 

 Rays also like those of Actinofjhrys project beyond the spines. 

 Both rays and spines in the immediate vicinity of the body are 

 enveloped in a stratum of exceedingly minute vibrio-like si)icules. 

 The green specimens of Acanthoci/stit;, independently of rays and 

 spines, measure about -jJ^th mm. in diameter; the colorless ones 

 measured about one-half the size of the former. 



Drawings were also exhibited of an Actinophryan, of which a 

 number of individuals lived together in colonies. These are not 

 unfrequently met with in the same positions as Acanthocystis and 

 Actino)<2?hserium. The species appears to be the same as that 

 recently described by Hertwig and Lesser, in the Archiv fur Mi- 

 kroskopische Anatomie,, 1874, plate iv. fig. 1, under the name of 

 Raphidiophrys eJegans. I have rej^eatedly met with the creature 

 in colonies from half a dozen up to forty. The whole colony moves 

 along with much greater rapidit}^ than Actinophrys sol. The in- 

 dividuals measure ^^gth mm. in diameter, and project a multitude 

 of rays extending to ith mm. in length. In colony the bodies are 

 conjoined by bridges or isthmi, through which chlorophyl balls 

 and granules incessantly but slowly pass from one to another. 

 The bodies and the bases of the rays are enveloped in an atmos- 

 phere of exceedingly delicate semicircular spicules. The animals 

 take their food in the same manner as Actino2')hrys sol. A colony 

 of thirty-eight was observed to break up into three separate colo- 

 nies numbering severall}- fifteen, ten, and thirteen, each of wiiich 

 moved awaj' in a different direction. 



Drawings were exhibited of Amoeba qitadrilineata, Carter, a 

 common species in the waters in the vicinity of Philadelphia. It 

 is about -vgth mm. in length b}- ^^gth mm. in breadth. The species 

 is remarkable especially for the retention of the four delicate lon- 

 gitudinal folds in all its movements. 



Drawings of two other species of Amceha were exhibited, which 

 are supposed to diflfer from those previously described. They w^ere 

 characterized as follows: 



Amceba viridis. Bright green from the multitude of contained 

 chlorophyl balls. Form of body irregularly stellate, with thick 

 conical pseudopods projecting in all directions. Sarcodic sub- 

 stance colorless and finely granular. Neither nucleus nor vacuoles 

 were observable. Movements slow. The bod}' occupied a space 

 of about ,'yth mm. The chlorophyl grains are nearly of uniform 

 diameter and measure the ^^qUi mm. Absecom Pond, New Jersey, 

 Nov. 5, 1874. 



Amceba tentaculata. Body spheroidal, oval, or limaciform, 

 projecting a multitude of long, conical, or fusiform pseudopods of 

 clear ectosarc, into which no granules of the entosarc enter ; pos- 



