5 e. — view into the internal cavity. 



PLATE XII. 



Fisf. 1. ExTRACRiNUS Briareus. 



1 a. — lateral aspect shewing the jointed, and intermediate lateral pieces, the rays, 

 tentacula, &c. 



1 J. — lateral view of a large specimen, in which are seen the abdominal pouch, the 



mouth, &c. In Dr. Buckland's Bridgewater Treatise there is a reduced figure 

 of this specimen. 



c, — jointed lateral and intermediate pieces shewing the manner in which the articula- 

 tions are secured. 



d. — specimen shewing the attachment of the column to the dorso-central plate, and 

 a rudimentary new joint, with an enlarged view of the same. 



e. — dorso-central aspect exhibiting the manner in which the first lateral pieces abut 

 against the dorso-central j)late. 



/.—enlarged view of the articulating facet of a full grown joint. 



g. — These figures represent the articulating facets of the ray joints at the second 

 bifurcations, and the projections for the attachment of the tentacula. 



h. — an auxiliary side arm. 



i, — portion of a column shewing the points of articulation for the side arms. 



h. — enlarged transverse view of a full grown columnar joint. 



2 I, — terminal ray joints with the hook-like appendages, (enlarged.) 

 m. — portion of a ray with tentacula attached (enlarged.) 



n. — enlarged view of the articulating facet of a columnar joint arrived at that stage 

 of growth bordering on maturity. 



0. — portion of a column exhibiting the full grown joints, with the smaller intervening 

 articulations. The articulating facet of one of the thinner joints is shewn 

 These latter are still less advanced in growth than figure n. 



p. — portion of a column. 



y. — portion of a column from a point more remote from the body than the preceding. 



T-. — the articulating facet of a columnar joint, with a rudimentary joint in the centre. 



