364 REPORT ON THE STATE CABINET. 



second, supporting the first supraradials, which are of moderate 

 size. The first interradial plate is comparatively large, commencing 

 just above the edge of the basal truncation, and supporting two 

 smaller plates above. Each of the first radial plates, on the part 

 just above the basal truncation, bears a strong central spine, with a 

 prominent rounded ridge on each side, extending to the upper 

 lateral margin and joining a similar ridge on the interradial plate, 

 and another ridge extends from the upper side of the central spine, 

 and joins a similar ridge on the succeeding plate ; this is continued 

 to the third radial, where it divides and extends on the supraradials. 

 The interradial plates of the first series are marked by similar 

 strong ridges, which culminate in a prominent node or short spine in 

 the centre. The finer surface markings are not known. Arms 

 unknown. 



The specimens occur in a magnesian limestone ; the test has been dis- 

 solved, leaving casts of the interior and impressions of the exterior 

 surface, and it is from these that we are able to derive the form and 

 character. This species is readily distinguished by its strong nodes 

 and ridges, and the spines upon the first radial plates. 



EUCALYPTOCRINUS CORNUTUS, Var. EXCAVATDS, HaLL. 

 PLATE XI, FIGS. 6, 7. 



This variety differs from the typical forms in having the base deeply and 

 broadly excavated ; the cavity embracing the basal, and nearly the 

 entire length of the first radial plates. The plates are marked by 

 ridges and nodes. In some of the specimens the second radial 

 plates are very imperfectly developed, being reduced to a mere 

 fiattened node which is entirely surrounded by the first and third 

 radial plates. 



In these specimens the dome has not been observed, and the arms and 

 axillary plates are unknown. The third radial plate is truncated above by a 

 long narrow plate, and the first interradial by two narrow plates separated 

 by a vertical suture, and has in all respects thus far the character of 

 the genus; but above this, the cavity appears to have been larger, and 

 shows no marks of the axillary plates, as usual in the dome of Eucalyp- 



TOCRINUS. 



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

 at Waukesha and Racine, Wisconsin. 



