773 
of Edinburgh , Session 1871-72. 
keel bifurcates, leaving a very characteristic diamond-shaped space 
in the centre towards the top of the joint. Two facets are thus 
formed for the insertion of two first radials. The number of arms 
is therefore ten. The arms are perfectly simple, and in our single 
specimen consist of twelve joints each. There is no trace of 
pinnules, and the arms resemble in character the pinnules of Rhizo- 
crinus. The first brachial is united to the second by a syzygial 
joint, but after that the syzygies are not repeated, so that there is 
only one of these peculiar junctions in each arm. The arm-grooves 
are bordered by circular fenestrated plates as in Rliizocrinus. 
Certain marked resemblances in the structure of the stem, in the 
structure of the base of the cup, and in the form and arrangement 
of the ultimate parts of the arms, evidently associate Bathycrinus 
with Rliizocrinus; but the differences are very wide. Five free 
keeled and sculptured first radials replace the uniform smooth ring 
formed by these plates in Rliizocrinus. The radial axillaries give 
off each two arms, thus recurring to the more usual arrangement 
in the order, and the alternate syzygies on the arms, which form so 
remarkable a character in Rliizocrinus , are absent. 
Only one nearly complete specimen and a detached stem of this 
very remarkable species were met with, and they were both brought 
up from the very greatest depth which has as yet been reached 
with the dredge, 2435 fathoms, at the mouth of the Bay of Biscay, 
200 miles south of Cape Clear. 
3. Laboratory Notes. By Professor Tait. 
1. On Thermo-electricity: Circuits with more than one Neutral 
Point. (With a Plate.) 
Having lately obtained from Messrs Johnson & Matthey some 
wires of platinum, and of alloys of platinum and iridium, I formed 
them into circuits with iron wire of commerce ; and noticed that 
with all, excepting what is called “ soft ” platinum, there is more 
than one neutral point situated below the temperature of low white 
heat, and that at higher temperatures other neutral points occur. 
This observation is, in itself, highly interesting ; but my first im- 
pression was one of disappointment, as I imagined it depended on 
some peculiarity of the platinum metals, which I had hoped would 
5 K 
VOL. VII. 
