408 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



is open, leaving large meshes or interspaces and is of the reticulate 

 type. The center of disk is occupied by plates forming a conven- 

 tional star, the tips of whose rays are the primary radial plates; the 

 interradii are large five-lobed primary ba,sal plates. The side of the 

 rays of this star is formed by a long slender ossicle. Within the 

 star is a pentagon of plates inclosing the central plate, which is at- 

 tached to the pentagon by short connectives, and the corners of the 

 pentagon are the basal plates. The carina! series consists of about 7 

 plates, the primary radial being elongate cordiform, the others prom- 

 inently four-lobed, except the last 2 or 3, which are irregular. These 

 imbricate so that a lobe extends laterally on either side. In contact 

 with the prominent inferomarginals, which form a flange to the edge 

 of ray, is a series of three-lobed superomarginal plates, which are 

 connected with the lateral processes of the carinals bj'^ 1 or 2 (second 

 and third carinals) slender ossicles. There are 7 supevomarginals, 

 and 5 of the transverse trabeculae, the last 2 superomarginals touch- 

 ing the reduced carinals (or sometimes the last lateral has no carinal 

 opposite). Two slender ossicles end to end extend from the first 

 superomarginal to the basal plate, close to the companion of the ad- 

 jacent ray, so that the inner ossicles of each series touch along their 

 whole length. These clasp the small madreporic body, which is on 

 the outer lobe of a basal plate (Ludwig's JRl). 



The inferomarginals, 7 in number, are much broader than long, 

 flat, slightly spaced, with a curved border bearing, 4 or 5 webbed, flat- 

 tened narrowly spatulate spines as long as the base line of comb, the 

 whole forming a flangelike ambitus. The outer end of the plate is 

 slightly broader than the inner and the transverse margins are 

 slightly concave. Parallel with the marginal series of spines and 

 close to them on the upper surface of the plate is a series of 3 or 4 

 very small spinelets scarcely visible until specimen is treated with 

 caustic potash. 



Papular areas in 2 series on each ray, the outer being "intermargi- 

 nal." The largest area is the proximal adradial. which has 8 or 9 

 papulae, while the others have 2, 3, or distally 1 papula. The larger 

 areas have several white grains scattered in the integument. 



The actinal intermediate plates are in general similar to Ludwig's 

 figure 23. A series of oblong plates, one interradial, is adjacent to 

 the inferomarginals. These are the largest intermediate plates. The 

 largest, interradial in position, is scalloped on the inner border and 

 constricted in the middle. The other 4 plates of each ray alternate 

 wdth the inferomarginals and the outer end underlies the inner end 

 of the marginals; moreover the plates are distinctly spaced. The 

 other actinal intermediate plates are in transverse columns. Three 

 columns start from the interradial and, bv branching variably, have 



