HETEROCRINIDAE 
107 
men it is about complete, attaining a length of 9.5 cm., and tapering to a narrow 
distal end. 
The outstanding character of this remarkable species is the relatively enormous, curved 
anal tube. It is represented by a wonderful series of six specimens, four of them having the 
tube intact, which are all figured, in order to show that the dwarfing of the fourth arm is no 
mere sporadic occurrence but a definite process ; a fifth, with the stem complete, has the tube 
plates displaced, and the sixth is fragmentary. Another striking character of this and some 
of the associated species is the great length of brachials in the median arm, and of the ossicles 
in the ramules — except the first which is always short — reaching sometimes five times their 
width ; this would seem to make for lessened flexibility in the arms. In two of the specimens, 
figures 3 and 4, I have been able to free the crowns completely from the matrix, so that in 
both all the lateral arms may be inspected and compared, and the abnormal position of the 
stem clearly seen — thus furnishing a full exposition of the essential characters of the genus ; 
in one the tube is visible from both sides. 
Horizon and locality. Eucalyptocrinus zone of Beech River formation, Brownsport 
group, Niagaran; Tuck’s Mill, Decatur County, Tennessee. 
Cremacrinus decatur new species 
Plate 28, fig. 7 
Similar to C. tubiilifcrns, but larger, the crown being 35 mm. high, with 
distal end incomplete. Median arm relatively stout, quite in contrast to that 
of the two preceding species; 2 long brachials of about 3.5 mm. are preserved 
beyond the short primibrach, and judging by the taper there were probably one 
or two more. Anterior arm has 6 axillary brachials in each ramus, giving off 
ramules with very long ossicles after the first alternately to a total of 12, and 
perhaps one or two more at the broken distal end ; interposed brachials mostly 
in series of two, the upper one often long enough for a third ; r. ant. arm less 
than one fourth the size of ant., and apparently branching only two or three 
times; IBr 2. Anal plates and tube not visible, only the anterior side being 
exposed. Stem stout, with long columnals, those beyond the proximal curve 
being 2.5 mm. long. 
The species is based upon a single very perfect crown, slightly broken at the distal end, 
and imbedded at one side ; if it had a curved anal tube it would stand rather close to the last 
species, but the strong median arm is characteristic. The difference in size of the anterior and 
right anterior arms is most pronounced, the area covered by the former being about five times 
that of the latter. It is from a much higher horizon than any of the other species, in a forma- 
tion that has yielded a number of crinoids with markedly distinct characters. 
Horizon and locality. Decatur limestone, Niagaran ; near Rise Mill, Perry County, 
Tennessee. 
Cremacrinus simplex new species 
Plate 28, figs. 8, 8a 
Of a very different aspect from any of the preceding, in the small number 
of arm-branches, and their dichotomous bifurcation, which might well warrant 
a reference to a new genus. Crown small, 28 mm. in height. Median arm fairly 
