8 Mr. W. Saville Kent on Prof. HE. Haeckel’s 
page, Prof. H. James-Clark was the first authority to point 
out the resemblance between the essential flagellate units of 
the sponge-body and the independant collar-bearmg monads, 
of which he was the discoverer, these results, so far as relates 
to the possession by the sponge-monads or Spongozoons of 
similar membranous collars, being confirmed by the observa- 
tions of Mr. Carter. It was clear, however, that it could only 
be through a much more extended and accurate acquaint- 
ance with the independent Discostomatous or collar-bearing 
forms that this question of the natural affinities of the sponges 
could be definitely and satisfactorily set at rest. It was en- 
tirely actuated by the ambition to become possessed of such 
accurate and extended information that the writer has de- 
voted the last six years to the study of this particular group ; 
and it is only fortified with the substantial fruits of this pro- 
longed investigation that he now approaches the obscure ques- 
tion of the nature and affinities of the sponges. Full details 
in reference to these investigations will appear in due course ; 
but it may be briefly stated here that a careful examination 
of members of each of the leading sponge-orders, Calcareous, © 
Siliceous, and Keratose, has pointed to one and the same 
general conclusion—namely, that sponges can no longer be 
regarded logically in any other light than as typical Disco- 
sTOMATOUS Protozoa. Not only in all structural points and 
in the remarkable form and function of the hyaline collar is 
the correspondence complete, but the phenomena of repro- 
duction and development are likewise essentially identical 
with what has already been observed of the simple and inde- 
pendent collar-bearing types. ‘The only essential distinction 
between the sponges and these last-named forms is, in fact, that 
while the latter, whether fixed or floating, solitary or aggregated 
in social clusters on a simple or branching pedicel, are invari- 
ably naked and fully exposed to view, the collar-bearing 
flagellate monads of the sponge-colony are as invariably con- 
cealed by and immersed within a sarcodie and usually spi- 
culum-secreting matrix. Practically, the distinction between 
the two groups is essentially parallel with what obtains be- 
tween the solitary or social “naked” Tunicata, Ascidiadce 
and Clavellinide, and those compound colony forms, the 
Botryllide, which are immersed and concealed within a 
gelatinous and not unfrequently spiculiferous matrix. And 
yet no one in his right senses would think of calling in ques- 
tion the propriety of uniting these two as members of the 
same primary class of the Molluscoida. In a similar manner 
it is requisite to unite as members of the same Protozoan class 
of the Discostomata the naked and independent collar-bearing 
