320 
Proceedings of Societies . [April, 
in acoustics analogous to the unit of quantity of electricity or 
quantity of heat, and which may be called the quantity of sound. 
In commencing their research the authors endeavoured to find a 
disk for the phonograph and telephone which would vibrate to 
the finest shades of sonorous vibration. They obtained the best 
results from a stretched membrane of thin india-rubber, rendered 
rigid by a cone of paper. 
March 6. — “ Preliminary Report upon the Comatulee of the 
Challenger Expedition,” by P. Herbert Carpenter, M.A., Assistant 
Master at Eton College. The collection of Comatulce made by 
the staff of the Challenger includes specimens from forty-five 
different localities, but few of which are deep-water stations. 
Comatulce were only obtained seven times from depths exceeding 
iooo fathoms. At lesser depths, 200 to 1000 fathoms, Comatulce 
were met with at thirteen stations ; but by far the greatest num- 
ber, both of species and of individuals, were dredged at depths 
much less than 200 fathoms, and often less than 20 fathoms, at 
twenty-six widely-distant stations. At the present time the 
author regards the collection as containing hi species, mostly 
new ; but as the work of examination and description progresses 
it is not unlikely that forms which he now considers different 
may turn out to be merely local varieties of one and the same 
species, so that the number given above may be subject to alter- 
ation. Of these in species, 59 belong to the genus Antedon, 
48 to Actinometra, 1 to Ophiocrinus, and 3, which are peculiar 
in having ten rays to the calyx instead of only five, to a new 
genus, for which he proposes the name Promachocrinus (Greek 
Promachos , “ Challenger”). In two of the species the rays are 
undivided, as in Ophiocrinus ; but in the third they divide, as in 
our common Antedon rosacea , so that there are twenty arms. 
The voyage of the Challenger has, according to the author, settled 
two curious questions in connexion with the Crinoids, the origin 
of which is due to Loven. They refer to Hyponome Sarsii, a 
so-called recent Cystid, and to Phanogenia, a supposed new 
genus of the Comatulidas. Hyponome turns out to be nothing 
more than the disk of a Comatula , minus its skeleton. The 
stellate condition of the centrodorsal in Phanogenia has long 
been a puzzle to the author, but the material brought home 
throws a considerable light upon it. This condition appears to 
be one of the concluding stages of a long series of changes in 
the shape and relations of the centrodorsal, which do not com- 
mence until some time after the loss of the stem, and the entry 
upon the free state of existence. The dredgings in Torres Straits 
brought up a considerable number of specimens of a hitherto 
undescribed Comatula. The author proposes to name it Actino- 
metra jfukesii. The examination of the Challenger Comatulae 
has entirely confirmed the opinions held by Dr. Liitken and the 
author respecting the distinguishing characters of Antedon and 
