New Orders and yew Families in the Class Echinodermata. 221 



DESCRIPTION OF THREE XEW ORDERS AND FOUR 

 NEW FAMILIES, IN THE CLASS ECHINODER- 

 MATA, AND EIGHT NEW SPECIES FROM THE 

 SILURIAN AND DEVONIAN FORMATIONS. 



By S. A. Miller. 



Order Agelacrinoidea, n. ord. and n. fam. 



This order is proposed to include, so far as known, only the family 

 Agelacrinidre, and each may, therefore, be defined as follows: 



Body thin, circular and parasitic upon other objects. The lower 

 side consists of a thin, smooth, attaching membrane or plate. The 

 upper side is more or less convex, and composed of thin, squamiform 

 or imbricating plates, usually much smaller at the peripheiy than 

 tow-'-d the center. Ambulacra constituting part of the convex sur- 

 feit furrowed on the interior, and composed of a double series of 

 transverse alternating plates, sometimes having smaller, middle, in- 

 tercalated ones. Two or more rows of ambulacra! pores connect the 

 exterior with the interior of each ambulacrum. The so-called ovarian 

 or anal aperture is situated in one of the inter ambulacral areas, and is 

 usually surrounded by cuneiform plates forming a depressed circular 

 prominence. The genera belonging to this order and family are 

 Agelacrinus, Edrioaster and Hemicystites. 



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Order Lichenocrixoidea, n. ord. and n. fam. 



This division of the fossil Echinodermata, and the famih' Licheno- 

 crinidae, are established upon the genus Lichenocrinus. 



The definition of the order and family will be the same, as both are 

 founded on a single genus. 



The bod}' attached during part or all of its life to foreign objects. 

 It is circular, convex upon the upper side, and more or less crateri- 

 form surrounding the central stalk like appendage. The lower side at 

 some period of life possessed a thin attaching plate. The upper side 

 is covered with numerous polygonal plates, without any evidence of the 

 presence of ambulacra, arms, mouth, pectinated rhombs or pores con- 

 necting the exterior with the internal cavity. The interior of the 

 visceral cavity contains numerous radiating upright lamellae that 

 support the polygonal plates of the upper side, and often leave their 

 impression, like the radiations of a star, upon the object to which it 



