102 
BULLETIN OF THE LABORATORIES 
ments of the lateral lobes are narrower than the intervening grooves, 
and supplied with three or four sets of indistinct nodules. 
Encrinurus deltoideus^ Shumard^ from the Cape Girardeau Lime- 
stone, Missouri, may be distinguished by its rounded extremity, its 
greater number of segments (24) along the mesial lobe, and also along 
the lateral lobes (8 segments). The segments of the lateral lobes are 
twice as wide as the furrows between them, and are devoid of nodules. 
Encrmurus nereiis^ Hall^ from the Racine beds of Wisconsin, may 
be distinguished by the greater number of segments (8 or 9) on the 
lateral lobes, as far as known not tuberculated ; judging by the figure 
of the type specimen a raised narrow, but distinct ridge runs along the 
lateral borders of the middle lobe. 
Encriniiriis Americmms^ Fogdes, from the Clinton Group of Geor- 
gia, may be distinguished by the smaller number of segments (6) 
along the lateral lobes ; the segments are almost twice as broad as the 
deep intervening grooves, are flat and even slightly grooved along the 
top, and are destitute of nodules, as far as known. 
Encrinurus elegantulus, Billings^ from the Anticosti Group of Can- 
ada, may be distinguished by the greater number of segments (24) 
along the middle lobes, the anterior 8 extending entirely across, the 
rest being interrupted, the free mesial space without tubercles. There 
are only 5 pairs of segments on the lateral lobes. They agree how- 
ever in the origin of the segments of the lateral lobes, when compared 
with the position of the segments on the middle lobe. 
Encrinurus ornatus, Hall and Whitfield, from the Guelph lime- 
stones of Ohio, may be distinguished (if the figures of the type speci- 
men are correct) by the segments of the lateral lobes having a less 
abrupt backward direction, and being all situated along the side of the 
middle lobe (whereas in E. Tliresheri the seventh pair extend posteri- 
orly from the same). The arrangement of the mesial tubercles along 
the middle lobe is also different, being situated on the second, fifth, 
ninth, thirteenth, seventeenth, and perhaps one on a later segment. 
If now the tubercle on the second segment be omitted the remainder 
are evidently seen to be separated each time by three segments ( instead 
of by two as in E. Tliresheri). 
Encrinurus punctatus, Wahlenberg, of Sweden and elsewhere in 
Europe, may be distinguished, it is said, by a single row of nodes 
along the middle of each lateral lobe (whereas the fourth segment of 
