1921] NATURAL SCIENCES OF PHILADELPHIA. 123 



I could not ascertain how the animalcule constructs the new 

 envelope. It seems likely that the naked individual, when already 

 fixed, can remain a very long time unprovided with any covering; 

 I found once a colony where all the animalcules, about six in number, 

 were naked, and three days afterwards, though living and ap- 

 parently in good health, only one of them was provided with a 

 capsule. It is interesting to note that the animalcule, as seen en- 

 closed in the shell, does not occupy the same position as he did 

 when free; the posterior point, from which arises the arcuated fla- 

 gellum, must have become displaced upwards and to the right, 

 at the same time that the body became free from the pedicle and 

 climbed up towards the opening of the shell. 



Salpingoeca polygonatmn sp. n. Plate VI, figs. 20-28. 



This small organism was found in the same locality as the last 

 one, at Pinchat, on the long filaments of Zygnema pectinatum, and 

 as a rule the threads were either abundantly provided with the 

 little Flagellate, or had none at all. 



The capsule (Plate VI, fig. 20-28) is about I7[i in length with a 

 breadth qf 43^2 to 5^;- only; it is nearly cylindrical for most of its length, 

 but is somewhat broadened at the aperture, and is rather abruptly 

 narrower behind, "^ terminating in a point which itself rests on a 

 thin, very short stalk; but note that, as in Histiona campanula, 

 the stalk is not a true pedicle, rather a root, which pierces the muci- 

 laginous sheath of the Zygnema and becomes attached to the cellu- 

 lose wall below. It may be observed at the same time that His- 

 tiona and Salpingoeca chose two different Zygnamas as a sub- 

 stratum, and that in the former of those animalcules the jelly coat- 

 ing was thicker than in the second; hence the longer stalk in His- 

 tiona. The protoplasmic body (Plate VI, fig. 20), cyhndrical in 

 shape, and about 10[l in length, looks as if hanging down inside 

 the cell, its upper end reaching as far as the aperture, while the 

 lower, rounded end is at some distance from the bottom. It re- 

 mains entirely quiescent, as a rule, but from time to time the httle 

 organism shakes weakly from head to foot, or suddenly retracts 

 to the very bottom of the shell. The nucleus, spherical with a big 

 central caryosome, is in the anterior part of the body, normally 

 between two layers of very small hyaline granules. The contractile 

 vesicle, rather large, has its place in the posterior portion of the 

 body. When the animalcule is seen somewhat retracted in the 

 shell, but still with its cylindrical shape, it proves to be deprived 

 temporarily of that special protoplasmic collar which is known 



^ The form is nearly that of the flower in the genus Polygonatvm, hence the 

 specific name. 



