THE GEOLOGIST. 



13 



The species at present known are, Woodocrinus macrodactylus 

 —the type species — W. expansus, W. goniodactylus, W. decodac- 

 tylus, and two others. There are imperfect remains of other 

 species, and also of another new genus, but the specimens yet 

 foimd are too imperfect to peimit us to form a satisfactory opinion 

 about them. 



Of all the species Woodocrinus macrodactylus is by far the 

 most common ; not more than three or four good specimens of the 

 others having been found among the accumulated debris of the 

 type species. 



The genus, which has been named after Mr. E. Wood, of Rich- 

 mond, the discoverer of the whole series, is related to the genus 

 Cyathocrinus of Miller, Taxocrinus of Phillips, Forbesocrinus of 

 De Koninck — differing in having five subradial plates ; while the 

 first has only four, and the second and third none. It appears also 

 to differ from Cyathocrinus in the mode by which the second radial 

 is attached to the first radial plate, and from the two last in having 

 the radial joints free, instead of being united laterally by inter- 

 radial plates. The calix or head of this genus is cup-like; 

 generally widely opened except in Woodocrinus decodactylus, 

 which is narrow and elongated, like a champagne glass. 

 Woodocrinus expansus slightly differs from the others in having 

 the shelly plates which form the cup, larger and thicker. 



Like all other Crinoides, the calix is composed of a series of 

 plates, which in this genus are quite smooth, and form themselves 

 into a star of five rays ; the base contains five plates, Altematiug 

 with these are five large hexagonal plates, called 'sub-radial;' 

 which in their turn alternate with five pentagonal plates, called 

 'radial;' superposed upon which are five more radial plates, 

 which are axillary, and from which spring two arms, which 

 bifurcate fi-om one to four times, according to the species. The 

 basal and sub-radial plates are united by their lateral edges. The 

 radial plates and arms are free. 



In Woodocrinus macrodactylus the arms bifurcate but once, and 

 are 20 in number; they are thick, cylindrical, and in appearance 

 not unUke the common earth-worm. In W. decodactylus they 

 are long and slender, and bifurcate twice, making the number of 

 rays 50. In W. expansus they bifurcate three or four times, and 



