19 



high. Third. primary radials a Httle larger than the second and 

 bearing upon the upper sloping sides the secondary radials. 

 There are two secondary radials in each of three radial series, the 

 second one being about twice as large as the first and bearing 

 upon each upper sloping side three tertiary radials, thus giving to 

 each of these three radial series four ai'ms. The radial series on 

 the left of the azygous area has one-half of it constructed in 

 the same manner; the other half, being the one most distant 

 from the area, possesses no tertiary radials, but has four sec- 

 ondary radials, and, therefore, in this series, there are only 

 three arms. The radial series opposite the azygous area has no 

 tertiary radials, but it has four secondary radials on each of 

 the upper sloping sides of the third primary radials, and, 

 therefore, there are only two arms in this series. The species 

 has only seventeen arm openina'S to the calyx. 



In each regular interradial area there are three plates, the 

 first of which are the larger plates of the calyx, and each one 

 has eight sides. It rests between the upper sloping sides of the 

 first primary radials and the second and third primary radials 

 abut it on each side, and it supports, on top, the other two 

 interradials. The upper interradials are never of equal size; 

 they are situated between the first secondaiy radials and below 

 the tertiaiy radials. 



The azygous area is subovate in form, and contains six 

 plates. The first one is in line with the first primary radials 

 and of the same size. It is followed by three plates, that differ 

 but little in size, and these are followed by two plates, in the 

 third range, that are situated between the second secondary 

 and first tertiary plates, and thus extend a little higher than 

 the plates do, in the regular interradial areas. 



In Batocrinus facetus the three armed series is on the right 

 of the azygous sjde, in this it is on the left. In that species, 

 there are four regular interradials and eleven azygous plates, 

 in this species, there are three regular interradials and six 

 azygous plates. It is a marked species that cannot be mis- 

 taken for any other one. 



Found in the St. Louis Group, in Hardin county, Kentucky, 

 and now in the collection of Wm. F. E. Gurley. The specific 

 name is in honor of the late Sidney S. Lj'on, who did so much 

 valuable work in this family of crinoids. 



