ZOOLOGICAL AND BOTANICAL ASSOCIATION. 21 



of fifteen joints, again bearing the third triangular plate, from which 

 springs a fourth subdivision ; to one of the branches of this division six- 

 teen more joints can be counted without any further branching, the 

 termination of this, the best preserved of the arms, being still wanting. 

 The plates composing these rays become more closely set and flatter 

 towards their upper part, their surfaces being marked by a continuous 

 double line or angular ridge. The rays, in consequence of the numerous 

 subdivisions, may in the perfect specimen have been fifty or more in 

 number. The delicate pinnules or tentaculae with which they are fur- 

 nished are not closely arranged, but attached to every alternate joint ; 

 they are about ■£$ of an inch in length, flattened and angular, curved, 

 and composed of about eight elongated joints. The stem or column is 

 composed of pentagonal plates, of nearly equal thickness, each having a 

 star-like, crenated, articulating surface, the external surface of each 

 angle being ornamented with a faint band of bead-like markings, which 

 become strong ridges, accompanied by a central depression or pit towards 

 the upper portion of the stem. At variable intervals, generally about the 

 eighth joint, sprung the ramules or auxiliary side arms, five in number, 

 developed from an articulating surface in the centre of each of the angles 

 of a joint; in the specimen under consideration they are mostly broken 

 off short ; the portions which remain show that they were round and 

 closely jointed ; an articulating surface of one of these ramules is very 

 well shown in the enlarged figure of a portion of the stem (Fig. 1, e). 



The plan of the arrangement of Plates, comprising the calyx 

 (Fig. 1, c) is taken from a well-pre3erved and larger example, in which, 

 however, the upper portion of the rays are absent. This specimen is 

 quite relieved from the matrix, and exhibits most perfectly the whole 

 of the plates of the head, with the lower subdivision of the arms 



(Fig. i, by 



Affinities and Differences. — This species somewhat resembles Penta- 

 crinus Milleri (Austin), but differs in several particulars. It is of 

 more delicate proportions: the branching of the rays takes place at 

 longer intervals : the tentacles are not so closely set : the stem, or 

 column, has sharper angles and square sides ; whilst in P. Milleri the 

 angles of the pentagonal joints are much rounded, and very prominent; 

 and again, the ramules, or auxiliary side-arms, in our species are situated 

 at greater distances. Pentacrintts scalaris of Goldfuss — said to be a sy- 

 nonym of P. Milleri — is a species found upon portions of the stem only, 



