114 THE ATLANTIC. [chap. ii. 



of these 8*5 centims. are occupied by the cup and the crown of 

 arms and 4*5 by the stem. As in P. asteria the basal joints of 

 the stem form interradial button -like projections, but the pro- 

 jecting bosses are very evidently pointed and slightly prolonged 

 downward, thus showing a tendency toward the depending proc- 

 esses which attain such remarkable dimensions in the liassic ge- 

 nus Extracrinus. The first radials are low and flat — shorter in 

 proportion to their width than in P. asteria and P.Mulleri; 

 the second radial and the radial axillary have much the same 

 form and relations as they have in the previously known spe- 

 cies ; as in P. asteria there is a true joint between the first and 

 second radials and a syzygial junction between the second radial 

 and the radial axillary. Tlie radial axillaries support two sym- 

 metrical first bracliials, which are connected with the second 

 brachials by a syzygy. From this point the branching of the 

 arms is very uniform ; each of the ten primary arms gives off, 

 as a rule, two secondary arms from the inside close to the base. 

 To take one arm as an example of this style of branching : the 

 radial axillary bears two facets right and left for two uniform 

 first brachials, which are united by syzygies to brachial axilla- 

 ries ; tliese latter have two facets of unequal size, the left facet 

 on the right joint and the right facet on the left joint being 

 small and supporting a simple arm, while the outer facet on 

 either joint supports a third radial, which is connected by a 

 syzygy with a second unequally facetted brachial axillary ; here 

 again the smaller facets are on the inside on each arm, and these 

 give off simple arms ; simple arms spring likewise from the 

 outer and larger facets, but these are considerably more robust, 

 and are evidently the continuations of the primary arms. Were 

 this mode of division absolutely constant, the number of arms 

 would be thirty, but the arrangement is slightly irregular, and 

 in the specimen procured thirty-one arms are present. 



The arms are more regularly semi - cylindrical and more ro- 

 bust than in P. asteria^ and they have rather a tendency to 



