of England and India. 19 
in this way, we shall never be able to get on without much con- 
fusion either in describing them or in distinguishing their spe- 
cies. Mere descriptions at this period of their history will not 
suffice, as those of Schlumberger testify (Ann. des Sc. Nat. t. 11. 
p. 254, 1845), especially where a single or only a few specimens 
of the species have been obtained, because numbers are required 
for comparison, to establish a species ; and although a figure may 
not be absolutely necessary with a great number of specimens of. 
the same species, it, for the same reason, becomes absolutely so 
with one or only a few of it. It is only by numbers that we can 
arrive at the typical form of the species, here as well as in the 
Rhizopoda generally, where those who are well acquainted with 
them know that the varieties are almost infinite. 
Appended to the descriptions will also be found “ Observa- 
tions,” in which any structural or physiological fact bearmg on 
the species only, or in connexion with the Rhizopoda generally; 
that appeared to me deserving of notice, has been mentioned. 
This is particularly the case under Difflugia compressa, a new 
and interesting species, which has been found so abundantly 
that I have been able to make out almost as much about it as 
about D. pyriformis. 
AMG@BA. 
Ameba princeps, Ehr. 
This species often occurs in Bombay as well as in Europe, and 
often with the villi on the posterior extremity, first pointed out by 
Dr. Wallich. I have given a description and illustrations of it 
(Annals, 1863, vol. xii. p. 30), chiefly for the purpose of pointing 
out the occasional presence in it of certain cells which appear to 
me to be reproductive elements; and have nothing more to add 
concerning it here, saving allusion to the corrections or altered 
views respecting the nucleus, which will be found at page 254 
of the same volume. 
Ameba quadrilineata, Cart. (Annals, 1856, vol. xvii. pl. 5. f. 3) ; 
A. radiosa (?), Duj. (bid. figs. 10-16) ; and A. verrucosa, 
Ehr., Annals, 1857, vol. xx. pl. 1. fig. 12. 
I have already figured these as they occur in Bombay. A. 
radiosa was only thus named provisionally; but since I have 
returned from India, and have seen Auerbach’s paper on the 
Amebe (Zeitschrift fiir wissenschaftl. Zoologie, Dec. 31, 1855), 
which just preceded my own in publication, it seems evident to 
me that this species would be better termed A. dbzlimbosa, which 
Auerbach has figured as a new species. 
Another Ameba to which I should allude here is that which 
I have delineated with the last-mentioned, and have also pro- 
Q* 
