WHAT IS BATHYBIUS ? 
353 
Usually of irregular shape, but occasionally assuming roundish 
forms. It consisted of a transparent jelly containing innumer- 
able, very minute, granules, many of which Prof. Huxley found 
to be equally soluble in dilute acetic acid and in strong solutions 
of the caustic alkalies ; but, in addition, there occurred some 
remarkable bodies to which great interest is attached. In the 
first instance Prof. Huxley noticed, adherent to the protoplasm, 
and occasionally embedded in it, numerous minute rounded 
bodies, soluble in acids, and to which he gave the name of 
Coccoliths. Still later, in addition to these Coccoliths, Dr. 
Wallich discovered, associated with the Bathybius, some 
larger spherical bodies of more complex organisation, which he 
designated Coccospheres. Yet more recently Prof. Huxley has 
re-examined his specimens under higher powers, and found his 
Coccoliths were of two classes — to which he now gives the re- 
spective names of Discolithus and Cyatholithus. The Discolithi 
he describes as oval discoidal bodies, with a thick strongly re- 
fracting rim, and a thinner central portion, the greater part of 
which is occupied by a slightly opaque, as it were, cloud-patch. 
The contour of this patch corresponds with that of the inner 
edge of the rim, from which it is separated by a transparent 
zone. In general the Discoliths are slightly convex on one side, 
slightly concave on the other, and the rim is raised into a 
prominent ridge on the more convex side.”* These objects 
usually range from -4 oVo 5"oVo their longest 
diameter. 
The Cyatholiths are like minute shirt-studs. They are 
stated to have ^^an oval contour, convex upon one face, 
and flat or concave upon the other. Left to themselves, they 
lie upon one or other of these faces, and in that aspect appear 
to be composed of two concentric zones surrounding a central 
corpuscule.” A lateral view of any of these bodies shows that 
it is by no means the concentrically laminated concretion it at 
first appears to be, but that it has a very singular and, so far as 
I know, unique structure. Supposing it to rest upon its lower 
surface, it consists of a lower plate, shaped like a deep saucer 
or watchglass; of an upper plate, which is sometimes flat, 
sometimes more or less watchglass-shaped ; of the oval, thick- 
walled, flattened corpuscule, which connects the centres of these 
two plates ; and of an intermediate substance, which is closely 
connected with the under surface of the upper plate, or more or 
less fills up the interval between the two plates, and often has a 
coarsely granular margin. The upper plate alwa}\s has a less 
diameter than the lower, and is not wider than the intermediate 
* On some Organisms from great Depths in the North Atlantic Ocean. 
• Quarteiiy Journal of Mici'oscopical Science^ Oct. 1868, p. 206. 
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