<)6 DAVENPORT ACADKMY OK NATURAI. SCIKNCKS. 



enclosed within the ring of first radials. It has 2\2 secojulary radials, 

 except in the anterior and the left i)ostero-lateral ray, which both, in 

 place of the second i)late, have large tertiary radials, and, in i)lace of 

 two, four i^rimary arms. 



The interradial plates are disposed in rows of one, two, and three; 

 arranged so as to form three circlets together with the second and third 

 primary radials and the first secondary ones, res[)ectively. The higher 

 interradials, which are smaller plates, and less prominent than those 

 described, extend to the ventral side, where they meet laterally with 

 similar plates from the axillary spaces, forming jointly with them the 

 greater part of the ventral covering. The azygous interradiiis is wider, 

 and consists of a larger number of [)iates, which are generally smaller 

 than their fellows at the four other sides, and their arrangement is less 

 regular. The anus is subcentral, somewhat bulging out toward the 

 i:)Osterior side, and extended into a proboscis. The oro-central i)late is 

 slightly excentric, and isolated from the ])roximals by a belt of small 

 pieces. The proximal plates are not connected among each other, 

 nor with the radial dome-plates, which also have a totally isolated posi- 

 tion. The arms are unknown. 



The column is of medium width, cylindrical; the central canal 

 large, obtusely pentangular, its angles directed interradially. 



Locality^ position, etc.: The tyi)e si)ecimens were collected by Rev. 

 W. H. Barris, of Davenport, from rocks of the age of the Hamilton 

 groui), at Alpena, Michigan, and are now in the author's collection. 



Remarks: In asking i)ermission of Dr. Uarris to describe this re- 

 markable species, it was my wish to draw attention to a very similar 

 form from Sweden, which has been described by Prof. Angelin in the 

 Iconogra])hia Crinoideorum Sueci;e, \). 27, and figured there under the 

 name of Polypeltes granielaiiis. The species was referred not only to 

 a separate genus, and separate family, but it has been made the tyjie 

 of a distinct suborder under the name of Poly)iicra., for possessing ap- 

 parently more than five basals. 



According to descri])tion, the Swedish sjjccies is comi)osed of "8 or 

 more basals, 16 parabasals, 10(?)xl radials" — all axillary — "numer- 

 ous interradial and axillary pieces," and as having "10x12 i)rimary 

 arms." It resembles, in general form and in the arrangement of its 

 plates, Megistocrinus concavns, and, as in that s[)ecies, the lower por- 

 tions of the calyx are concave, but seem to have been obscured in the 

 type specimen. In the American species the concavity includes the 

 two lower primary radials, the lower series of interradials, and the cor- 



