50 
SMITHSONIAN INSTITUTION 
legmen plates in good condition, together with some additional structures connected with the 
anus, and traces of ambulacra. 
In numerous examples the base is well exposed, so that the position of the small basal 
can be observed. Jaekel and Bather have stated that this is not a reliable character for the 
genus, and Jaekel declares it is not constant in C. bacca. These specimens show that it is 
thoroughly constant for the species, but that its position is not in accordance with the general 
rule in crinoids with an unecjually tripartite, monocyclic base, namely, left anterior (or 
7 o’clock). On the contrary it is here uniformly at the left posterior (lo o’clock, pi. ii, figs. 8, 
21, 22), whereas in C. rosaceus, as shown by my specimens, it is normal. The former appears 
to be the case in the specimen figured in the Camerata monograph, pi. 75, figs. I5a-c; but 
through misunderstanding a note was inserted in the explanation of fig. 15a stating that it is 
drawn with the anal side at the left lower corner (which would make it according to rule), 
whereas it is actually at the right lower corner. Fig. c, the posterior view, shows this by the 
position of the interhasal suture, which would be to the right of the interradial suture if the 
explanation was correct. 
Now the tegmen of C. hacca appears to he considerably dififerent from that of the typical 
C. rosaceus. Instead of being suboral plates succeeded by the large triangular plates, as in that 
species, and as heretofore supposed in this, the interambulacrals are themselves almost tri- 
angular, the lower face obtusely angular to fit directly into the notch formed by the sloping 
shoulders of the radials, while above they are extended to an acute angle, so that when in 
normal position they would form a low pyramid. But instead of interlocking at the apex they 
leave a considerable open space in the middle, and are also not in contact laterally, but are 
parted by open clefts running between tbeir edges to the arm bases, along which traces of side 
pieces of ambulacra can occasionally be seen (pi. ir. figs. 6 to 18). 
The large tegmen plates are analogous in position to orals, and that is probably the 
proper term for them. Four of them are of like shape and size, but the fifth remains to be 
accounted for. The central vacant space seen in all the specimens is of the proper size and 
position to lodge the posterior oral, pushed in between the other four by the anal structures, 
as in the tegmen of many Camerata illustrated by Wachsmuth and Springer on plate 3 of their 
monograph, and precisely as seen in that of Culicocrinus figured herein on plate ii, figure 4c. 
It is evident that this tegmen was of rather fragile construction, as the central plate is in- 
variably wanting, and the ambulacra only represented by traces. Thus the tegminal structure 
differs also from that of Haplocrinus and Culicocrinus, in the fact that the plates of the ven- 
tral pyramid in those genera are closely joined, those of Culicocrinus without any grooves, 
and those of Haplocrinus with superficial grooves at their edges, not for ambulacra, but as 
mere receptacles for the arms, as herein now showm for the first time in H. mespiliformis 
(pi. 25, figs. 28, 29, 290. See also Devonian Crinoids of New York. pi. 40, figs. 10-14). 
There is also a very material difference in the anal structure of the two forms. In 
Coccocrinus there is a simple opening at the base of the posterior oral. In C. bacca the anus 
is at the end of a short protuberance, of which we often find one plate, and sometimes one or 
two more succeeding it, in place above a large posterior plate flanked by a smaller plate at 
either side. In one specimen four plates in this .series are visible, leading to the opening. 
The two flanking plates served as a strong support, for we frequently see them, and the inter- 
vening posterior plate standing firmly upright, while all other plates of the tegminal arch 
have fallen down (pi. ii, figs. 10-20). 
The evidence is complete to prove that the structure of C. bacca is different from that 
of C. ro.<;accus in three major characters, viz. : the composition of the tegmen, the anal struc- 
ture, and the position of the small basal. From this it follows that they cannot be retained 
in the same genus. Accordingly I am proposing for the Tennessee species the new genus 
Lyonicrinus, in memory of Col. Sidney S. Lyon, who was an ardent student of the crinoids, 
and author of many notable genera and species from the Kentucky-Indiana area. 
