XXII. 
CHARACTERISTIC DEEP-SEA TYPES. — RHIZOPODS. 
THERE must be, all over the bottom on which reticularian 
rhizopods have been found, thousands of undiscovered minute 
protozoans which have no solid tests. On account of the diffi- 
culty of examining on the spot the samples of bottom as they 
are brought up, we can only conjecture the physiology of these 
lowest types, which will undoubtedly be discovered whenever the 
proper methods for examination are employed. In the mean 
time, we must be satisfied with a knowledge of the types which 
have become known to us from their tests; but even these 
do not explain the structure of their animals; this is known 
to us only by comparison with that of their shallow-water 
allies. 
No special report of the “ Blake” Foraminifera has as yet 
been completed, but I am fortunate in being able to extract from 
the admirable memoirs of Brady on the * Challenger” Fora- 
minifera, and of Dr. Goés on the Rhizopoda of the Caribbean, 
deseriptions and figures of the prineipal types collected by us. 
Dr. Goés, during a stay of several years at St. Bartholomew, 
explored a considerable area with the dredge, to a depth of 
400 fathoms, and, owing to the existence of extensive sunken 
plateaux and steep sloping banks, where the temperature falls 
rapidly, he was able to collect the majority of the types which 
we subsequently brought together from deeper waters, but which 
extend upwards to depths of 200 fathoms, or 150 even, and 
perhaps less. 
Of the rhizopods the siliceous radiolarians play an unimpor- 
tant part in the bottom deposits of the district explored by the 
* Blake." A few surface species were collected in the track of 
the Gulf Stream. Yet, judging from the well-known radiola- 
