A MONOGRAPH OF THE EXISTING CRINOIDS 21 



Dr. Torsten Gisl6n in 1924 described in detail many of the structural details of this 

 form. 



This species was recorded by me in 1929 from off Penang, hi 1933 from two 

 localities near Java, and in 1934 from New Harbour and Singapore. 



Dr. Torsten Gisle"n recorded two specimens from Pulo Condor, Cochin China, in 

 1936. 



Genus BASILOMETRA A. H. Clark 



Basilometra A. H. CLARK, Temminckia, vol. 1, 1936, p. 304 (diagnosis; genotype B. boschmai, new 



species) . 

 Rhadinometra GiSLfiN, Kungl. Fysiogr. Sallsk. Lund Forh., vol. 7, No. 1, Aug. 11, 1936, p. 2 (new 



genus from French Indo-China), p. 15 (genotype R. dawydovi, new species). 



Diagnosis. A genus of Colobometridae including large, but slender, species in 

 which the arms are 80 in number, 120 mm. long; the IIBr series are 4 (3+4), the IIIBr 

 series are 2, and the outer division series are 4 (3+4), all with occasional exceptions; 

 the cirri are long and moderately stout, 35 mm. long with 47-49 segments; the dorsal 

 processes on the cirrus segments are so slight that the cirri appear practically smooth 

 in lateral view; P 1( P 2 , and P 3 are similar and of the same length, very stiff and rigid, 

 23-24 mm. in length with 17 or 18 segments; P 4 is similar, but shorter; the pinnules 

 on the division series are shorter and less rigid than the proximal arm pinnules; P a is 

 always absent; P I( P 2 , P a , and P b are usually absent on the inner arms on each IIBr 

 series. 



The single species in this genus has a very characteristic facies, suggesting a slender 

 armed species of Heterometra with the pinnulation of a large species of Colobometra. 



Geographical range. From Ternate northward to Cochin China and Cambodia. 



Bathymetrical range. From the shore line down to 15 meters. 



Remarks. In its very slender division series and arms, in the character and 

 interrelationships of its proximal pinnules, in the absence of certain proximal pinnules, 

 in the proportions of its cirri, and in the slight development of dorsal processes on the 

 segments of the latter Basilometra bears a rather striking resemblance to the very 

 much smaller and more delicate Epimetra, though in the latter all the division series 

 are 2, and the cirrus segments bear dorsally a delicate median ridge, which may be 

 paired. 



It is probable that Basilometra and Epimetra are rather closely related, and that 

 both are somewhat more distantly, though still closely, related to Pontiometra. 



Gislen said that because of the combination of curious cirri, mode of arm ramifi- 

 cation, slender arm bases, defective pinnulation, and characteristic proximal pinnules 

 this type is clearly distinguished from every other comatulid. In regard to arm rami- 

 fication it comes nearest to Petasometra, from which it differs in the following particu- 

 lars: The centrodorsal is subconical instead of discoidal; the cirri are very numerous, 

 with numerous segments; the spinosity of the cirrus segments is unique; division series 

 are present up to IVBr series; the IIIBr series are usually 2; the arms are slender, and 

 the arm bases widely separated; the brachials are long, and the distal intersyzygial 

 interval is 3 muscular articulations; the pinnulation of the inner arms is very defective; 

 and the proximal pinnules following P P have spinous distal ends, suggesting those 

 in Heterometra. 



