87 



FAMILY GLYPTASTERIDiE. 



GLYPTASTEE MILLIGAN^, n. sp. 



Pate V, Fig. 7, azygous side of a small specimen; Fig. 8, side 

 view of a larger specimen; Fig. 9, summit 

 view of same. 



Species variable in size. Calyx obpyramidal, truncated below 

 only the size of the column. Plates highly convex. Radial ridges 

 imperfectly defined. Higher than wide. Interradial areas flattened 

 below and depressed between the arms. Surface smooth or finely 

 granular. Column pentagonal. Columnar canal small and slightly 

 cinquefoil. 



Basals form a small pentagonal disc, with the angles directed 

 toward the center of the subradials. Subradials large, longer than 

 wide, having an angular ridge directed toward the center of each 

 adjoining first radial and one toward an angle of the basal disc. 

 A transverse section is pentagonal, with the angles at the center 

 of the subradials, and re-entering angles at the sutures, as in the 

 basal disc below; but from the center of the first radials upward, 

 a transverse section is pentagonal, with the center of the radials 

 in the angles. First radials rather larger than the subradials and 

 a little wider than long. The one on the left of the azygous area 

 hexagonal, the others heptagonal. Second radials much smaller 

 and hexagonal. Third radials smaller than the second, axillary 

 and support the free arms. 



The first regular interradials are large, rest between the supe- 

 rior sloping sides of the first primary radials, and are followed by 

 two much smaller plates in the second range, which unite with 

 smaller plates that graduate to those of the vault, without any dis- 

 tinct line of separation. One can hardly say whether or not the 

 third range should be classed with the plates of the vault. The 

 first azygous plate truncates a subradial, and is followed by three 

 plates in the second range, that unite with plates which should, 

 probably, be classed with those of the vault. 



The vault is depressed, convex toward the center and sunken 

 toward the interradial areas. It is covered with numerous convex, 

 polygonal plates, and bears a subcentral azygous orifice. There 



