48 



DOLATOCRINUS APLATUS, n. Sp. 



Plate III, Fig. 16, basal view; Fig. 17, summit view; Fig. 18, 

 side view. The suture lines are too indistinct on the 

 vault of our specimens for illustration. 



Species medium size, very short or much depressed, vault 

 and calyx subequal in capacity, Calyx low, more than three 

 times as wide as high, rounding out from a deep basal cavity 

 and spreading, without any constriction, to the free arms. 

 Surface deeply sculptured. Radial ridges very small but made 

 somewhat conspicuous by the elongated nodes at the center of 

 each plate. 



Basal plates within the cavity of the calyx and extending as 

 high as the base of the free arms. First primary radials are 

 entirely within the basal concavity. Second primary radials 

 short, quadrangular, two or three times as wide as high. 

 Third primary radials, short, pentagonal, axillary and each 

 supports on one of the superior sloping sides four secondary 

 radials, and upon the other a single secondary radial which is 

 axillary and bears upon each upper sloping side four tertiary 

 radials, by which arrangement, there are three arms to each 

 ray. There are, therefore, fifteen arms in this species, and 

 fifteen ambulacral openings to the vault. 



The azygous area is like the other areas. The first inter - 

 radials are somewhat elongated, have nine sides and are 

 broadly truncated above for the second interradials. Instead 

 of a central node, on each plate, there is a central excavation, 

 from the margin of which the plates are radiately sculptured. 

 The second plate is sbout one-fourth as large as the first and 

 it is followed by two small plates in the third range that 

 unite with the plates of the vault. 



The vault is subcorneal and bears a subcentral orifice at the 

 summit. Probably the orifice might be said to be at the top 

 of the proboscis, but the proboscis is not the sixteenth of an 

 inch high, and hence, appears only as a slight elevation for 

 the azygous opening. The sutures on the vault, in our speci- 

 mens, are so badly obliterated that it is impracticable to attempt 

 to describe the plates. There are four ovarian slits between 

 each radial series, and two between each of the ambulacral 

 openings, which arrangement gives to this species forty ovarian 

 apertures. 



