108 
PALEONTOLOGY OF NEW-YORK. 
Arms corresponding in structure to those of the preceding species; the 
plates slightly interlocking along the centre, and rectangular on their 
outer margins. Armlets opposite and originating at every fifth, sixth, 
or seventh plate of the arm, composed of a double series of wedgeform 
plates. Tentacula originating on the outer edges of the plates of the 
armlets : joints of tentacula nearly twice as long as wide. Secondary 
tentacula unknown. 
Column very long; consisting, near the body, of alternating large and 
small joints (the larger being the thicker ones); and farther from the 
body, of several thin joints between the thick ones, and sometimes 
presenting little difference in the thickness or diameter of the ar¬ 
ticulations. 
The conspicuous differences between the preceding and this species are the strongly 
ridged plates of the latter, while in the other they are but inconspicuously marked 
in the same manner. The first radial plates of J\I. nobilissimus are proportionally 
longer than in this species, and the armlets are more closely arranged ; also the 
column attached to the base consists of numerous thin plates, while in this species 
the first joints below the base are thicker, with a very thin and scarcely conspicuous 
one alternating. Of the present species, some ten or more individuals, in various 
states of preservation, have been seen, and these are all of nearly the same size. 
Three specimens of M. nobilissimus have been found, each one having about the 
same dimensions as those figured. 
Specimens of this species were found at Schoharie some thirty years since; and 
the first published notice appeared in the Schenectada Reflector newspaper in 1835, 
wdiere the specimen fig. 1 of Plate in was figured and designated under the name 
of Actinocrinus polydactylus. In the same year, in an article in Silliman’s American 
Journal of Science (Yol. xxvii, p. 363), this crinoid is referred to as the “ Stags- 
horn encrinited ’ Subsequently, in 1840, Mr. Conrad noticed this fossil as Astrocrinites, 
and in 1841 as Astrocrinites pachydactylus. In 1843, Mr. Mather published a figure 
of the specimen, fig. 2, Plate hi, from the Cabinet of Union College, under the same 
name. No description of genus or species has ever been published, so far as I am 
aw r are. The generic name Astrocrinites cannot be retained, for reasons given under 
generic synonymy; and in adopting a new generic designation, I have retained the 
specific name of pachydactylus , that name having appeared in the Annual Reports 
on the Geology of New-York and in the Final Report of Mr. Mather : and the 
reference of this fossil to a described species Actinocrinus polydactylus in the Sche¬ 
nectada newspaper cannot, impose the adoption of that specific name, as it might 
have done had the publication been made in a scientific journal. 
