358 REPORT ON THE STATE CABINET. 



assumes an ovate form with attenuate base, yet the species here described 

 has a much larger number of plates, which are differently disposed. 



Formation and Locality. — In limestone of the age of the Niagara group 

 at Waukesha, Wisconsin. 



GENUS APIOCYSTITES, Forbes. 



Apiocystites imago, n. s. 



PLATE XII, FIG. 12; PLATE XII a, FIG. 9. 



Body irregularly elliptical, about three-iifths as wide as long, a little 

 larger above than below the middle. Basal plates occupying more 

 than one-fourth of the entire height of the body. Second range 

 consisting of five large plates. In the third range the plates are 

 about half the size of those of the second range. The fom-th range 

 consists of at least six plates ; the two over the ovarian aperture are 

 smaller than the others. The fifth range consists of six plates of 

 smaller size than the others, and of a pentagonal form, the upper 

 margins being determined by the number of apicial plates, which 

 are unknown. The ovarian aperture is situated over the right 

 superior angle of the hexagonal basal plate, and the space is exca- 

 vated from the upper margin of the plates of the third range and 

 the lower margin of one of the fourth range. The pectinated 

 rhombs upon the right side of the ovarian aperture occupy the 

 adjacent margins of two plates, and are on the same parallel with 

 the aperture. The other pectinated rhombs are not preserved in the 

 specimen. The plates of the four lower ranges are longitudinally 

 ridged in the middle, and in their perfect condition have probably 

 had a central node. The circa-ovarian plates, and those of the centre 

 of the summit or apex, have not been determined. 



The specimen described is a cast, but so well preserved as to indicate 

 very satisfactorily its most important characters. It is a more elongate 

 form than any cystidean of this group (Pseudocrinites, Apiocystites, 

 etc.) that I have seen from American rocks. 



Formation and Locality. — In the Racine limestone of the Niagara group 

 at Racine, Wisconsin. 



