374 REPORT ON THE STATE CABINET. 



The above description is drawn from internal casts. This species 

 differs from G. nobilis in the much greater length of calyx which is not 

 contracted in the lower part, while in that species it is broad and spread- 

 ing. It appears not to have had a proboscis ; but in the casts there is 

 the filling of a cavity which has passed from the summit of the dome 

 between the posterolateral arms, where it turns outwardly, as if it had 

 opened on the exterior surface in the form of an anal aperture. 



Geological Formation and Loealitij. — In rocks of the age of the Niagara 

 group ; Racine, Wisconsin. 



GENUS LAMPTEROCRINUS, Roemer. 

 Lamptebocrinus inflatus, Hall. 



PLATE X, FIG. 6. 

 Balanocrinus inflatus, Hall. Report Progress Geol. Survey Wisconsin for 1860, p. 22. 1861. 



Body below the arms sub turbinate, with sides somewhat inflated in the 

 lower part ; arm-bases prominent, leaving deep interbrachial spaces ; 

 dome low, strongly inflated on the anal side, surmounted by a slender 

 subcentral proboscis. Basal plates small, pentagonal. Subradial 

 plates proportionally large, hexagonal. First radials heptagonal, a 

 little larger than the subradials ; the form of the second and third 

 radials undetermined ; the second are as large as the subradials ; 

 the third very small. Interradial plates, six ; the first hexagonal, as 

 large as the second radials, with two in the second range, and three 

 in the third range, uniting with the dome plates. Anal plates 

 numerous ; form and arrangement unknown. 



The above description has been drawn from the internal casts of 

 several specimens, which exhibit the division of the plates. 



This species differs from B. sculptus, Troost ; Lampterocrinus tennesseen- 

 s/s, Roemer (^Silurian Fauna of Western Tennessee), in being more distinctly 

 turbinate or obconical ; in the deeper interbrachial spaces ; the inflation 

 of the dome on the anal side ; and in its uniformly smaller size. 



