318 EIGHTEENTH REPOKT ON THE STATE CABINET. 



lar form follow in direct succession : and upon the third is a fourth plate 

 supporting one or two arms. Between the upper sloping faces of the plates 

 of the second range, there is inserted a pentagonal plate, which supports a 

 range in direct succession of two or three hexagonal plates. The summit is 

 unsymmetrical, and in one specimen there is an apparent central aperture 

 or mouth, and an excentric or ovarian aperture; and the margin is marked 

 by what appears to be the bases of slender arms or tentacula. 



Such a structure in the ordinary nomenclature of the Crinoidea would 

 be described as a range of basal plates, succeeded by a radial series of four 

 or five plates. 



The distinctly unsymmetrical form of one of the species having this 

 structure, together with the peculiar character and parts of the summit, 

 give it a decidedly cystidean aspect ; while it cannot be allied with the 

 crinoidean genera at present known. 



CRINOCYSTITES CHRYSALIS (n. s.). 



Body small claviform, unsymmetrical, gradually enlarging from the base 

 for half its length and then swelling a little more rapidly, and again con- 

 tracting more abruptly towards the summit. The expansion being greater 

 on one side, while the other is nearly straight or a little concave, gives 

 an unsymmetrical form. 



There are about six ranges of plates : the lower range being compara- 

 tively long, the number unknown ; the second range consists of elongate 

 heptagonal plates which, on their upper truncate faces, support in direct 

 series three smaller hexagonal plates, and above the last one there is 

 apparently a small arm-bearing plate. Between these direct series of 

 plates there is an intermediate or interradial series of three plates 

 alternating with the others, the upper ones of which are pointed above, 

 allowing the fourth plate of each of the adjacent radial series to join at 

 their lateral margins, giving but five plates in the range immediately 

 below the summit. The summit is unsymmetrical, showing evidence of 

 two apertures and five slender arms or tentacula. 



Surface of plates striate. 



Formation and locality. In limestone of the age of the Niagara group 



at Racine, Wisconsin. 



CRINOCYSTITES? RECTUS (n. s.). 



Body subcylindrical, rounded below ; basal plates of medium size ; those 

 of the second range much larger, and supporting three other plates 

 . in direct superposition, the last one or fourth plate of the series sustain- 

 ing two small arm plates. The intermediate range consists of four plates 

 in direct succession, the last one narrowed above and lyine between the 



