ov4 Reviews—Prof. J. S. Newberry—On Edestus. 
IV.—On tee Srructure anp Rewtations or Hprstus, WITH A 
Description oF a Gigantic New Spescizs. By Prof. J. 8. 
Newserry, M.D. (Annals New York Acad. Sci. vol. iv. No. 4 
(1888), pp. 1-10, pls. iv.-vi.) 
HE discovery of a new gigantic example of the remarkable 
fossil spine, Hdestus, in the Coal Measures of Mason County, 
Hlinois, affords Prof. Newberry the opportunity of again reviewing 
the characters and possible relationships of this anomalous fish- 
fragment. ‘The memoir is one of much interest, and refers to nearly 
all the points hitherto ascertained, except Trautschold’s discovery of 
the occurrence of the fossil in Russia. It would, however, have 
added much to the completeness of the discussion, if a microscopical 
section had been prepared ; for if Hdestus consists of ‘‘ dense bone” 
(p. 0), it is certainly not a Selachian dermal appendage, and if it has 
the well-known structure of the latter, it is useless to speculate as to 
its pertaining to a Ganoid (p. 4). From various other considera- 
tions, Prof. Newberry concludes that the original fish must have 
been a Selachian; and the fossil is regarded as an undoubted spine. 
The latter must have been “ buried in the integuments throughout 
its entire length; the enamelled denticles alone projecting above 
the surface to form a saw, which would be a terrible weapon, if 
placed upon some flexible portion of the body where it could be 
used with freedom and power. ‘The extremity of the spe may 
have lain in a sheath from which it could be partially erected by 
muscular action, and used as the lancet of the surgeon fish 
(Acanthurus) is; but the bilateral symmetry of Edestus proves that 
if employed in this manner it must have been located on the upper 
margin of the tail or back.” The arrangement is considered to be 
best explained—perhaps precisely paralleled —by Trygon, in which 
“‘a considerable number, sometimes five or six, defensive spines are 
set in the place of the posterior dorsal fin. They come into use in 
succession, like the fangs of venomous serpents. As the anterior 
one loses its denticles or becomes worn or broken, it falls, and is 
succeeded by another from behind. Yet several may be in existence 
and effective at the same time, all arising from a common segmented 
bony base which grows by additions to its posterior extremity.” 
The new spine of Hdestus giganteus is at least 18 inches in length, 
by 74 inches in breadth, and indicates the enormous dimensions to 
which the fish must have attained, if this ingenious explanation 
proves true. ACTS sie 
FEwEs @ ive SS) AlN eb) | ee © Czar D> aie iS 
——_@—_—__ 
GEOLOGICAL Society or Lonpon. 
J.—June 6, 1888.—W. T. Blanford, LL.D., F.R.S., President, in 
the Chair.—The following communications were read :— 
1. The following letter from H.M. Secretary of State for India 
accompanying some specimens of rubies in the matrix from Burmah :— 
“India Office, Whitehall, S.W., 2nd June, 1888.—Sir,—I am: 
directed by the Secretary of State for India in Council to present to 
