of 'England and India, 2S 



above stated, which formed a slimy layer over the surface of a drain 

 adjoining a heath-bog. Out of upwards of 200 specimens, the 

 largest average size was that above given. There is considerable 

 variety of shape, even to that of a circular figure (k) ; but all have 

 the characteristic compressed form (c) from which I have designated 

 the species ; all present a light brown colour, and most of the 

 tests have that peculiar collar-like mark (//) round the neck 

 above mentioned. Neither the nucleus nor the vesiculse could 

 be seen in situ, on account of the opacity of the tests ; and until 

 one is found sufficiently transparent to admit of this, these points 

 must remain undetermined. I did not meet with a single spe- 

 cimen of D. pyriformis among those of D. compressa where the 

 latter so abounded, although they are both very plentiful at 

 their respective localities in the same neighbourhood, and both 

 in ditches draining the same heath-bog; but vih.\[e,D. pyriformis 

 prevailed among dead leaves only, D. compressa was chiefly found 

 in company only with the conjugating Algae mentioned. Still 

 I found specimens of D. compressa with D. pyriformis, and am 

 now inclined to believe that those which I have considered to be 

 D.proteiformis, Ehr,,in my "Observations" on D. pyriformis {I.e. 

 p. 250), were specimens of D. compressa, the compressed form 

 of which would easily be mistaken for globularity ; for, when 

 passive, this species always rests on its broad surface, and its 

 compressed form is not seen until it be turned over, or until the 

 animal becomes active and assumes the erect position. Further, 

 I am inclined to think that they must have been specimens of 

 D. compressa because this species is so generally distributed 

 throughout the same neighbourhood, and, lastly, because they 

 did not present the " deep olive or greenish colour " which I 

 now find (ap. Pritchard) is one of the characteristic features of 

 D. proteiformis. It is true that the size of D. proteiformis is set 

 down (/. c.) as much less than that of D. pyriformis and that of 

 D. acuminata, Ehr.; but this matters little, and the characteristic 

 form also of D.proteiformis, viz. "ovate subglobose," is so near 

 that of D. pyriformis, that there remains no specific difference 

 that I can now see, to disunite these so-called species. Thus, 

 after all, D. pyriformis, Pcrty, may be but a larger and more 

 elongated form of D.proteiformis, Ehr., in which case the original 

 name should be retained for the typical form, whichever that 

 may be. 



On submitting D. compressa to pressure, and crushing the 

 test in water under a glass cover, as stated in my paper on D. 

 pyriformis, the animal part was found to consist of protoplasm 

 charged with colourless moleculse, small brown cells, yellow oil- 

 globules, starch- granules, the nucleus, certain large cells which 

 I shall provisionally term " reproductive," and portions of food 



