MONOGRAPH OF THE EXISTING CBINOIDS. 557 



This form of oral, in greater or lesser perfection, is very characteristic of this 

 species and persists up to the time of the disappearance of these plates. 



Speaking of the larvae of Promachocnnus kerguelensis, which I loaned him 

 for study in connection with his work on the Crinoidea Flexibilia, Mr. Frank 

 Springer writes that the origin and development of the radianal as shown in 

 Comactinia is paralleled in this species. 



The series studied by him begins with the prebrachial stage, in which the 

 radials have just appeared as small dots, but, contrary to what is the case in the 

 youngest C'omactinia, all of them are present, though that of the right posterior 

 ray is smaller than the others and much smaller than the radianal to the left of it. 



Mr. Springer thinks it probable, as I have suggested, that the radianal actually 

 develops before any of the radials are formed. 



In the succeeding stages the radianal does not increase to the relative size 

 to which it attains in C ornactinia, but it runs a similar course until it is lifted out 

 from the ring of radials by the growth of the anal tube and the interradial spaces 

 have been occupied by the interradial radials characteristic of this genus. 



ANTHOMETRA ADRIANI. 

 Fig. 938, p. 549. 



Among the numerous pentacrinoids brought home by the Gauss were two 

 evidently belonging to Anthometra adriani. The characters of these are as 

 follows : 



No. 1 : Dredged on September 27, 1902, in 385 meters 



The seven columnals immediately following the calyx are short and discoidal, 

 progressively decreasing slightly in diameter distally. The topmost columnal is 

 slightly longer than that just below it, to which it is very closely joined. 



Broadly speaking, the calyx and columnals resemble those of Promachocrinus 

 kerguelensis at the same developmental stage. In profile the sides of the calyx 

 are nearly straight, diverging from the topmost columnal at an angle of somewhat 

 less than 90. 



The basals are large and conspicuous. The left distal side of the posterior 

 basal is half again as long as the right distal side. 



The radials, which are broadly in apposition laterally, are about as long in the 

 median line as the interbasal sutures. On the distal borders of the radials just 

 below the proximal angles of the IB^ on either side there are a few conspicuous 

 more or less webbed spines. 



The radianal is unusually long and narrow. From a base extending from 

 the proximal left corner of the IB^ on the right posterior radial to halfway 

 between the posterior interradial suture and the base of the IBrj on the left pos- 

 terior radial it extends diagonally upward, gradually narrowing, to a position just 

 over the interradial suture (in the mid-interradial line), where it ends in a blunt, 

 rounded point on a level with the distal end of the IBr : . 



