182 ' BULLETIN 76, UNITED STATES NATIONAL MUSEUM. 



iiitcrbrachial arc the plates bear a median transverse series of four to six flattened 

 lanceolate appressetl spinules, which are gradually reduced in size and number 

 along ray, being frequently absent from the last few plates, and only one or two 

 beyond the middle. 



Adambulacral plates with an angular furrow margin bearing a palmate series 

 of five or sLx more or less compressed spinelets, the median (or adoral admedian) 

 the longest and most compressed; tips rounded; lateral spinelets often with flat 

 side uppermost. The furrow series is contmued along adoral and aboral margms 

 of plate in three or four spaced, stout, much smaller, papilliform spinelets. On 

 actmal surface one, two, or occasionally three, enlarged very robust bluntly pointed 

 spuuiles stand in a transverse oblique, or longitudinal series (only one spinule in 

 medium-sized and small specimens). Between them and furrow series is a semi- 

 circular row of three or four shorter, blunt, stout, papilliform spinelets, or some- 

 times very strong!}' flattened spinelets; these sometimes absent; on outer part of 

 plate are several smaller three- or four-sided unequal clavate spinlets. Exclusive 

 of furrow series there are about fifteen to twenty-two spmules and spinelets to 

 each plate, the outermost very irregular in distribution and on distal part of ray 

 showing a tendency to group themselves about the two or three larger spinules. 



Mouth plates prominent actinall}-, with a bristlmg armature of robust, short, 

 untapered blunt spmes ilisposed in a raargmal and two actinal series. Of the latter 

 one stands on the border of the median suture, wMle the second, an intermediate 

 shorter irregular series, is located between it and a continuation of the marginal 

 series on the edge adjacent to first adambulacral. These spines are subquadrate, 

 subterete, occasionally spatulate, and are longer on the inner than on outer end of 

 plates. They are also variable in number according to age and locality. The true 

 marginal series consists of about seven robust spines in addition to a large median 

 unpaired spine at the inner angle of the combined plates. The three adjacent 

 to inner angle are usually graduated in size, then the next four are stouter and 

 longer. Tliis is the plan of the furrow series; the spine counts vary. 



Actinal interradial areas large, the intermediate plates extending to the tenth 

 to seventeenth inferomarginal, or one-fourth to a little over one-third length of 

 ray measured along side from interradius; plates arranged in rows running from 

 adambulacrals to inferomarginals. From inner side these plates are oval and 

 imbricate with all the surrounding plates. Plates armed with unequal, swollen, 

 more or less crowded granules, those in center robust and clavate, often with slightly 

 flaring tips bent outward, the peripheral smaller, round-tipped, occasionallj' sub- 

 prismatic, very unequal and irregular, and radiating over narrow shallow grooves 

 between the plates. These channels lead in an irregular course from the infero- 

 marginal fascioles to those between the adambulacral plates. In some specimens 

 they are more conspicuous than in others, and all are more conspicuous adjacent to 

 adambulacrals where they are often roofed by pectinate pedicellaris. ilany of 

 the plates bear a central enlarged pomted spinule directed toward margin. The 

 number of plates bearing such spinules is variable. 



Madreporic bodj^ small, situated one-third distance from center to margin; 

 striations very irregular, the ridges between striae coarse. 



Anatomical notes. — Superambulacral plates present, extending along ray as 

 far as do the intermediate plates, and absent from first ambulacral ossicle; they 



