

MONOGRAPH OF THE EXISTING CRINOIDS. 



FIG. 69. 



127 



FIG. 70. 



Fio. 73. 



FIG. 71. 



FIG. 72. 



FIGS. 69-74. 69, PERFORATED PLATES FROM TUE SKIN OF OAUDINA PLANAPETURA, SHOWING A CLOSE APPROXIMATION TO THE 

 PRIMITIVE TYPE OF ECHINODERMAL CALCIFICATION (AFTER II. I,. I'LARK). 70, A PERFORATED PLATE FROM THE SKIN OF CAU- 

 DINA CALIFORNICA, SHOWING INCIPIENT CALCAREOUS RODS (AFTER H. I*. CLARK). 71, TlIE APICAL SYSTEM "F A YOUXIJ 

 SPECIMEN OF EUROCIDARIS NUTRIX FROM THE ANTARCTIC, SHOWING THE PRIMITIVE CENTRAL PLATK SURROUNDED II V FIVE 

 GENITALS (CORRESPONDING TO THE CRINOID BASALS), BEYOND WHICH ARE FIVE OCULARS (CORRESPONDING TO THE c 

 INFRABASALS). 72, THE APICAL SYSTEM OF A SPECIMEN OF L.YTECHINUS VARIEGATUS FROM FLORIDA, SHOWING THE CENTRAL 

 PLATE RESOLVED INTO NUMEROUS SMALL PLATES AND SURROUNDED BY FIVE GENITALS (CORRESPONDING TO THE I IllXmii 

 BASALS), BEYOND WHICH ARE FIVE OCULARS (CORRESPONDING TO THE CRINOID INFRABASALS), THE TWO PO8TXBIOB BXAI IIINc; 

 THE PERIPROCTAL AREA BETWEEN THE GENITALS; THE MADREPORIC PORES ARE NOT CONFINED TO THE RIGHT ANTERIOR 

 GENITAL, BUT OCCUR ALSO ON THE TWO ADJACENT OCULARS. 73, THE APICAL SYSTEM OF A SPECIMEN OF -\RBACIA STKLLATA 

 FROM MARGARITA ISLAND, LOWER CALIFORNIA, SHOWING THE CENTRAL PLATE DIVIDED INTO FOUR, AND THE RIGHT ANTERIOR 

 GENITAL, ORDINARILY A MADREPORIC PLATE, RESOLVED INTO NUMEROUS SMALL PLATES. 71, DIAGRAMS ILLUSTRATING THE 



PROGRESSIVE CHANGES DURING GROWTH IN THE RELATIONSHIPS OF THE ELEMENTS OF Till: < AI.Y.N. AMI IN THE RELATION- 

 SHIP BETWEEN THE CALYX AND THE VISCERAL MASS OF A COMATULID; THE EXTREME ATTAINED BY THE AHULT PENTACBIN1TE 

 IS REPRESENTED BY E: THE PLATES SHOWN ARE THE BASALS, THE RADIALS, AND THE ORALS. 



