THYSANOCRINID^. 209 



angles of the basals ; the truncated part sharply pentangular, and com- 

 pletely occupied by the column. Basals very large, as long as wide, and 

 angular above j the posterior one considerably longer, and its upper face 

 truncated. Radials fully twice as large as the first costals, and somewhat 

 larger than the basals. Second costals smaller than the first, and facing out- 

 ward, the sides slightly incurving; their sloping upper faces unequal, the 

 shorter side bearing a lateral arm, and the longer one a row of distichals. 

 The higher orders of brachials, which are roofed over by rigid covering 

 pieces, are formed into tubular appendages, from w^hicli at intervals armlets 

 are given off alternately. The second arm starts from the third distichal, 

 and it is probable that each succeeding arm is given off from the third plate 

 of successive brachials. The appendages are preserved in the specimens 

 only to the first palmar. Interbrachials : 1, 2, 3; the first as large as the 

 first distichal ; those of the second and third row much smaller. Anal side 

 a little wider and bulging from below the base of the free rays upwards ; the 

 anal plate, which is even larger than the first radials, is followed by three not 

 very large plates, and these by successive rows of three plates each, wdiich 

 pass into the anal tube ; the plates of the middle row are marked by a con- 

 spicuous angular ridge, which extends from the angles of the column to the 

 base of the anal tube, and runs parallel to the ridges upon adjacent radials 

 and costals. Ventral disk elevated; composed of few rather large, con- 

 vex or slightly nodose plates, which are continuous with the interbrachials. 

 The anal tube is constructed of similar somew^iat smaller plates ] it is cen- 

 tral, but bends abruptly to the anterior side of the calyx ; its length not 

 known. Orals not larger than the other plates of the tegmen ; they are 

 excentric, being pushed completely to the anterior side. Column near the 

 calyx sharply pentangular, with a small node at the angles of each joint. 



Horizon and Locality,. — Upper part of the Niagara group ; Decatur and 

 Wayne Cos., Tenn. 



Ti/pes in the Mineralogical Museum at Breslau, Germany. 



SIPHONOCRINUS S. A. Miller (redefined, W. and Sp.). 



1888. Miller; Amer. Geologist, Vol, L, p. 263; and 1889, Amer. Geol. and Pal^ont., p. 281. 

 Syn. Eticalyptocri?ius (?) — McChesney, 1859 ; Descr. New Species, p. 95. 

 Syn. 6^/^i9^m>.2^5 — McChesney ; Chicago Acad. Sci., 1868, Vol. I., p. 23 ; and Hall, 1861; Rep. 



of Progr. Geol. Surv. Wise, for 1860, pp. 21 and 22 ; and Hall, 1867 ; 20tli Rep. N. York State 



Cab. Nat. Hist., p. 328. 



27 



