380 Dr. T. Wright on new Species of Echinodermata 



If we seek further for resemblances to our Brittle-star, we must 

 look for them more amongst the beautiful Ophiocomce of our 

 seas than among any forms we are acquainted with in the fossil 

 state, but even between it and them the differences are many and 

 distinct. 



Locality and stratigraphical range. — This beautiful fossil was 

 collected by the Rev. A. W. Griesbach from the Forest marble of 

 Oundle, Northamptonshire, where it is rare. We have dedicated 

 this species to that gentleman, to whom we are indebted for 

 much valuable information relative to the stratigraphical distri- 

 bution of Echinoderms in his county, and likewise for a liberal 

 contribution of materials to aid us in the completion of these 

 memoirs. 



Pentacrinus Goldfussii, Wright. PI. XIII. fig. 3. 



Diagnosis. — Calyx composed of a central pentagonal plate, five 

 small heart-shaped pieces, and five large triangular basal ele- 

 ments; rays thick, strong and bifurcated; total number of 

 their subdivisions unknown ; the five primary rays consist of 

 two pieces, the basal piece is flat, and has a slightly elevated 

 portion about the centre of the upper surface, the brachial 

 piece is strong and triangular, its base resting firmly on the 

 former ; the sides of the triangle support two arms ; the ten 

 secondary rays consist of from ten to eleven circular pieces 

 with smooth unequal undulated surfaces, whereby their thick- 

 ness is rendered very unequal; the secondary rays support 

 twenty tertiary rays, which have the same general character 

 as the secondary rays; the number of pieces entering into the 

 composition of each is unknown ; from the fragmentary state 

 of this part of the specimen the number may be estimated at 

 from fifteen to twenty pieces. The column near the calyx is 

 composed of thin, deeply divided five-rayed plates, with well- 

 marked transverse articular impressions on their surfaces ; 

 every fourth plate is thicker, broader, and more prominent 

 than the one above it or below it ; the side arms are numerous, 

 and composed of thin circular plates : the lower part of the 

 column is unknown. 



Description. — This beautiful Sea Lily is remarkable among its 

 Liasic congeners for the comparative strength and thickness of 

 its rays ; the centrum of the calyx is simply a thickened and en- 

 larged columnar joint to which the upper part of the column is 

 articulated ; around the apices of the rays of this centrum five 

 small heart-shaped basal pieces are inserted, the points of which 

 are directed outwards ; they are very convex externally, project- 

 ing from the surface of the calyx, and have the appearance of 



