ECHIXODERMATA. 277 



FAMILY GOMPHOCYSTIL^E.— Gomphocystites. 



FAMILY HOLOCYSTTD^.— Crinoeystites, Holocystites. 



FAMILY HYBOCYSTID^E.— Hybocystites. 



FAMILY LEPADOCRIXID^E.— Apiocystites, Callocystites, Echino-encrinites, Glyp- 



tocystites, Lepadocrinus, Pleurocystites, Sphaerocystites. 

 FAMILY UXCERTAIX.— Eoeystites. 



ORDER BLASTOIDEA. 



FAMILY XUCLEOCRIXID^E.— Xucleocrinus. 



FAMILY PEXTREMITID^E.— Blastoidocrinus, Granatocrinus, Pentremites, Troosto- 



crinus. 

 FAMILY STEPHAXOCRIXID^E — Codaster, Codonites, Eleutherocrinus, Stephan- 



ocrinus. 



ORDER PERISHO-ECHINID^E. 



FAMILY ARCHyEOCIDARID^E.— Archaeocidaris, Eocidaris, Lepidocldaris, Pholido- 



eidaris. 

 FAMILY LEPIDECHIXID^.— Lepidechinus, Lepidesthes. 

 FAMILY PAL^ECHIXID^.— Melonites, Oligoporus, Palaechinus. 



ORDER ASTEROIDEA. 



FAMILY P A L^E A STERTD^B , — Onychaster, Palaeaster, Palaeasterina, Petraster, 

 Schaenaster, Stenaster. 



ORDER OPHIUROIDEA. 



Eugaster, Palaeocoma, Protaster, Ptilonaster, Teeniaster. 



ORDER AGELACRINOIDEA, n. ord. and n, fam. 



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

 iphery than toward the center. Ambulacra constituting part of the convex surface 

 furrowed on the interior, and composed of a double series of transverse alternating plates, 

 sometimes having smaller, middle, intercalated ones. Two or more rows of ambulacral 

 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 Hemicy6tites. 



ORDER LICHENOCRINOIDEA, n. ord. and n. fam. 



This division of the fossil Echinodermata, and the family Lichenocrinidae, 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 body attached during part or all of its life to foreign objects. It is circular, con- 

 vex upon the upper side, and more or less crateriform 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 connecting the exterior 

 with the internal cavity. The interior of the visceral. cavity contains numerous radiating 



