THE RECENT CRINOIDS OF AUSTRALIA — CLARK. 787 



Ends of the basal rays visible as slight tubercles ia the angles 

 of the calyx ; radials prominent, strongly concave anteriorly, and 

 somewhat produced in the interradial angles ; I Brj^ oblong, twice 

 as broad as long, the lateral edges straight; I Brg broadly penta- 

 gonal, about half again as long as the I Br^, the anterior angle 

 rounded, the lateral edges straight continuing anteriorly the 

 lateral edges of the I Br^ ; in life the I Br series are probably just 

 in apposition, but the component segments are sharp, not as yet 

 having become flattened against each other. 



Ten arms about 20 ram. long ; the brachials are mostly wedge- 

 shaped and about as long as broad ; the first two are slightly 

 larger than the others ; the brachials are all rounded dorsally, 

 with no trace of carination. 



Syzygies occur between the third and fourth, seventh and 

 eighth, and usually the eleventh and twelfth (sometimes the 

 ninth and tenth or tenth and eleventh) brachials, and distally at 

 intervals of usually two oblique muscular articulations, though 

 frequently one syzygial pair immediatel}'^ follows another. 



PPj, 2> find 3 are small and weak, very short, equal iu length 

 to a syzygial pair and one other brachial, composed of five 

 segments, the first about as long as broad, the remainder rather 

 longer than broad ; these pinnules taper gradually from the base 

 to the tip ; P4 and the following pinnules are about half again as 

 long and much stouter, composed of about seven ossicles, the first 

 two short, the remainder rather longer than broad ; the first three 

 segments are stout, the pinnule thence tapering rather sharply to 

 the tip ; the segments are rounded dorsally, but are rather sharply 

 convex, foreshadowing their ultimate prismatic shape. 



Sacculi are large and closely set along the ambulacra. 



The colour is light purple, the perisome deep purple. 



There is as yet no trace of any ambulacral skeleton. 



Dr. H. L. Clark described these young specimens (wath others 

 somewhat more advanced) as a new species in the genus Himero- 

 melra. The straight sides of the elements of the 1 Br series, the 

 tapering cirri, and the uniformity of the proximal pinnules, 

 together with the perisomic plating, especially on the pinnules, 

 seen in the larger specimens, the distribution of the syzygies, and 

 the abundance and large size of the sacculi, as well as the very 

 characteristic musculature show conclusively that these specimens 

 cannot be any species of Himerometra, young or old, but that 

 they must belong to the genus Plilometra ; in fact if one can for 

 the moment overlook the obsolescence or al)sence of carination on 

 the outer part of the arms and on the pinnules — a character 

 always late in making its appearance — the relationship is at once 

 evident. Dr. Clark says, — "Fortunately, however, there are 



