MONOGRAPH OF THE EXISTING CRINOIDS. 



89 



Internodes.— In the pentacrinites, the sections of the stem between the nodals (see 



fig. 127, p. 197). 

 Interpalmar. —Sume as Interamhulacral. 

 Interpalmar areas. — See Interamhulacral areas. 



Fig. 62. 



no. 63. 



Fio. 6-1. 



Figs. 62-64.-62, Diagram showinq the analysis of a chiasma and tue comparative relationship between a chiasma 

 and the central nervous structures (fig. 64) (drawing by the author). 6.1, diagram showing the course of the 



NERVES IN METACRINUS ROTUNPUS (DRAWING BY THE AUTHOR). 64, DIAGRAM OF ONE OF THE FH'E NERVE UNITS OF THE 

 CRINOIDAL DORSAL NERVOUS SYSTEM, SHOWING ITS INTERRELATIONSHIPS WITH THE ADJACENT SIMILAR NERVE UNITS (DRAWING 

 BY THE AUTHOR). 



Inter pinnulars. — Small porisomic plates sometimes developed between the bases of 

 adjacent proximal pinnules when these arc incorporated in the body wall. 



Interpolated arm division. — ^Arm division in which the division series are redii]>li- 

 cations of the first two or first four ossicles of the free undivided arm, as in 

 most of the recent comatulids (see figs. 61a-c, p. 87). 



79146° — Bull. 82—15 7 



