506 FOSSIL INVERTEBRATED ANIMALS. 



spring from the indentations of the corresponding vertebrae — 

 which are formed of fine cyhndrical branches of equal length, 

 and composed of small pieces, all cylindrical, pierced with a 

 little hole, and whose succession forms a canal which commu- 

 nicates with one of the lateral holes of the vertebra, or joint of 

 insertion. On the lower side of the last articulations are found 

 four small crustaceous tubercles^ two at each extremity, the 

 latter of which has the form of a crook. As to the body, or 

 umbel, it is composed of five rays, or arms ; the base of which 

 supports the sort of testaceous section of which we have spoken 

 above : this base is short, and formed of three articulations only. 

 Each ray is then subdivided into two branches, and those into 

 two or three others, but without much regularity. These 

 branches, secondary and tertiary, are formed of a vast number 

 of small articulations, rather decreasing in diameter than in 

 height ; on each side of which springs a barbie of half an inch 

 in length, and the twentieth of an inch in breadth, and which 

 is similarly formed of a great number of httle pieces. All the 

 articulations, small and great, are round or convex below, but 

 flat above, with a longitudinal groove, deep in the middle, and 

 furnished with two ranks of suckers, as in the asterias ; and 

 we shall be less astonished at the great quantity of articulations 

 of the encrinus found in the bosom of the earth, when we are 

 told that Guettard, who amused himself by reckoning the num- 

 ber of articulations in an individual scarcely twenty inches 

 long, found them to amount to twenty-five thousand seven 

 hundred and thirty-five ! As to the very varied formation 

 exhibited by the entrochi found in the earth, we must also 

 observe that, on the same living individual, some are found 

 almost round, so very little are the angles of the pentagon 

 marked \ some are evidently pentagonal ; others are in the form 

 of stars, with fine rays, more or less distinct ; and, finally, there 

 are some smaller ones, which are channelled in one half of their 

 diameter. 



These animals, in the living state, very probably inhabit the 



