August 1, 1884.] 



SCIENCE. 



105 



in the abandonment of this idea. Certain forms of 

 crinoids, as Pentacrinus, Democrinus, and Bathycri- 

 nus, are peculiar to great depths, and form in our seas 

 numerous and widely separated colonies. 



A recent species of Pentacrinus, a genus largely 

 represented in the lias and oolite, was brought in 

 1755 from Martinique to Paris, and described by 

 Guettard. At long intervals rare specimens from 

 the Caribbean Sea have been seen. On the 21st of 

 July, 1870, Gwyn Jeffreys, while dredging from the 

 Porcupine at a depth of two thousand metres, in 

 longitude 39° 42', latitude 9° 43', procured a score 

 of specimens. It would seem as if their excellent 

 state of preservation would prove whether they 

 were free or fixed. Thomson, who studied them, 

 believed that the animal lives slightly attached to the 

 soft mud, changing at will its abode, and swimming 

 by means of its feathery arms. On the Talisman, 

 the trawl was twice dropped to depths occupied by 

 this Pentacrinus; and we decided, contrary to the 

 prevailing opinion, that these animals live firmly 

 fixed by the backward-curving tendrils, which grow 

 from the terminal joint of the rod. These hooks, 

 as it were, solder themselves to the bottom, and can 

 be detached only by breaking. 



We have attempted to show in our plate the char- 

 acter of the bottom of the sea on which Pentacrinus 

 lives, as it was shown by the dredging made opposite 

 Rochefort, at fifteen hundred metres. Pentacrinus 

 Wyville-Thomsoni in considerable numbers covers 

 the ground, forming a kind of living meadow, from 

 which rise large Mopseas. The rocky ground was 

 covered with beautiful corals, resembling flowers 

 with the calyx opened ; and in the midst of this liv- 

 ing world moved hitherto unknown crustaceans 

 (Paralomis microps A. M. Edw. ) whose carapace was 

 ornamented with fine spines. Actinometra (crinoids 



which become detaclied from their rods after full 

 growth) were floating in the water, or fastened them- 

 selves for short intervals by their tendrils to the 

 brandies of the Mopseas. Pentacrinus and Acti- 

 nometra were of a beautiful grass-green, the Mopseas 

 of an orange color, the corals of a deep violet, and 

 the crustaceans of a mother-of-pearl whiteness. This 

 profusion of life, and this prodigality of colors, at 

 fifteen hundred metres below the surface, certainly 

 form two of the most wonderful facts which have 

 been reserved for the naturalist to discover. 



In 1827 Thomson found attached to Comatulas 

 (free crinoids with no attaching rod) a Pentacrinus 

 of small size, which he described under the name of 

 Pentacrinus europaeus. This animal seemed to 

 possess, in all the details of its structure, the char- 

 acteristics of the fossil Encrinus and of the modern 

 Pentacrinus. Ten years later Mr. Thomson, when 

 again examining a small crinoid, was much aston- 

 ished to see it suddenly abandon its rod, and be«rin to 

 swim with its arms for some time, and then to re- 

 attach itself by its tendrils. Continuing his studies, 

 he saw the arms, originally branched at the summit, 

 gradually assume the character of the arms of Coma- 

 tula; and he was gradually brought to the knowledge 

 that Pentacrinus europaeus was only a young Coma- 

 tula. 



Comatulas are numerous at certain points on our 

 coast, where they are found, according to their age, 

 gracefully clinging among the sea-wrack, or sheltered 

 under the pebbles accumulated on the reefs. Sev- 

 eral species descend to a considerable depth, one being 

 found abundantly at twelve hundred metres. At 

 some places we saw Comatulas existing by thousands, 

 and representing almost exclusively the animal life 

 of the locality. 



RECENT PROCEEDINGS OF SCIENTIFIC SOCIETIES. 



New-York academy of sciences. 



June 3. — Mr. G-. F. Kunz read a paper on a new pro- 

 cess of cameo or intaglio gem- engraving, in which he 

 said, that, from his first experience in the dental chair, 

 he received the impression that the machine used in 

 tooth-drilling would be the proper one for engraving 

 and cutting on stones similar to cameos and intaglios. 

 In the engraving-lathe at present used, the tool re- 

 volves on a horizontal shaft, to which are attached 

 tools of different size and shape; the Italians and 

 French using a screw-thread, while the English make 

 use of a lead head, which is simply fastened in by the 

 revolving of the wheel. A set of tools or drills often 

 numbers over a hundred. Mr. Kunz exhibited the 

 S. S. White improved dental engine, which is some- 

 what similar to the other machines in use, and may 

 be described as follows : A driving-wheel eleven inches 

 in diameter is set in motion by a foot-treadle ; and 

 from this wheel the power is conveyed, by means of a 



cord of fibre or thin leather, to a pulley-head. To this 

 is hinged a pivot-rod, extending from it as a flexible 

 arm, which conveys the power to the drill through 

 a steel or iron head-piece. The main advantage lies 

 in the revolving-point being allowed so much free- 

 dom of motion by the flexible wire arm. that it can 

 be placed in any position desired, and held in any 

 position on the work instead of the work being held 

 on it. Any revolving-tool that can be placed at 

 will on the work, in any desired position, gives the 

 desired result; and this can be attained by a flexible 

 driver, as in this machine. Ir n ight, however, be 

 improved. 1°. The points or drills should be made 

 of softer iron, to hold the particles of diamond-dust 

 more readily. 2°. The tool should be arranged to 

 w r ork more steadily, and thus overcome any possible 

 jar in very fine work, although it has drilled a series 

 of holes in a metal plate, which no engraver with the 

 old lathe could place more closely. 3°. The driving- 

 wheel should be heavier and larger, to attain more 



