56 



T'.RIKF KKSI'MK. 



Til tile ten l>ullctiiis III' till' Illinois Stiitc' Museum nf Natural His- 

 tf)ry, coninicncinii- with the third and t'lidiiig with the iircsciit one. 

 the authors have (h'KiK'd. I'min llio palaeozoi*- rocks of I lliiiois. and 

 adjacent states, one new ()rder. the ( 'onularida, (ixc lu'w families. 

 Knchostomid;v. Mitrocrinidie. Pleurocystida'. Por(x-riui(hi' and Thal- 

 ainocri niche, and ten Jiew gi-nera. Aesioc-ystitcs, Bidcinnocystitos, 

 Tihurella. Enii)erocrinus. Eiicliostonia, Indiaiiocrimis, Mitrocrinus, 

 Sampsonocrinus. SInimardocrinus and 'riiahimocrinus. 



\Vc have (h'scribed and illustrated more than four hundred new 

 species of fossils, nearly all of which Ixdonu; to the Ivdiinodermata. 

 Beside, we have redescribetl and illustrated several s])ecies of other 

 authors which had been imperfectly described or not illustrated. 

 While doin.n' this work, covering: a [)eriod of nearly four years, wc 

 liavc had the oijportunity of (>xaniining the principal collections to 

 be found in these states, and w(> have, as we thiidv, discHivered many 

 things relating to the structure of crinoitls that were before unknt)wn. 

 The work must, however, speak for itself, as to our definition of the 

 anatomical parts, and the supjjosed biological functions iJerforined 

 by them, and the supposed place in the scale of nature to which we 

 havi' rcd'erred the animals. 



