98 Trans. Acad. Sci. of St. Louis. 



EXPLANATION OF ILLUSTRATIONS. 

 Plates I-VI. 



Plate I. — 1. Interarabulacra of Melonites multiporus. — 2, Interambu- 

 lacra of Melonites crassus (type specimen) . — 3, Interambulacra of an 

 Oligoporus from the Warsaw Limestone at Boonville, Mo. 



Plate II. — 4, Interambulacra of Melonites multiporus. — 5, Interambu- 

 lacra of a small Oligoporus from Boonville, Mo. 



Plate III. — 6, Interambulacra of Melonites multiporus, showing the 

 genital plates. — 7, Interambulacra of Melonites multiporus. 



Plate IV. — 8 a-e, Interambulacra of Melonites multiporus. — 8 f , Teeth 

 of Melonites multiporus figured in 8 a-e. — 9 d, Apical system of Melonites 

 multiporus figured on PI. V., figs. 9 a, b. 



Plate V. — 9, Melonites multiporiis. Interambulacra of a large specimen 

 showing the successive enlargement of the individual pieces. — 10, Inter- 

 ambulacra of Melonites multiporus, showing the same feature. — II, Apical 

 system ot Melonites multiporus (?) (Magnified two diameters). — 12 d, 

 Apical system of Melonites multiporus figured on PL VI., figs. 12 a-c. 



Plate VI. — 10 c, Interambulacrum of Melonites multiporus showing the 

 mode of lateral expansion by the deposition of rings of calcareous sub- 

 stance. — 12, Interambulacra of Melonites multiporus. — 13, Interambulacra 

 of Melonites multiporus. 



Issued May 5, 1904. 



