ECHINODERMATA — CLAKK. 025- 



(rarely tenth and eleventh), and subsequently at intervals of two, 

 or more commonly one, oblique muscular articulations. All the 

 brachials are smooth and rounded doisall}--, and not only do the 

 plates not overlap, but they are scarcely in contact (except at 

 syzygies, of course). Pinnules rather few, twelve-fifteen on each 

 side of an arm, widely spaced, owing to length of arm-joints and 

 frequent syzygies. First pinnule (PI. xlvii., fig. 4) stout, borne 

 on second brachial, 2-3 mm. long, of seven joints, which are 

 smooth and semi-cylindrical ; first two about' as wide as long, 

 third, fourth and fifth longer than wide ; terminal joint minute,, 

 blunt. Second pinnule (PL xlvii., fig. 5) borne on fourth 

 (epizygal) brachial, very short, about a millimeter long, of 

 only four joints; succeeding pinnules (PI. xlvii., fig. 6) less 

 stout, with eight-fourteen joints, the basal ones large but 

 only a little expanded laterally. Sacculi abundant and 

 large, especially in distal pinnules; very few on disc. When 

 dry, the disc shows many small calcareous plates, largest and most 

 conspicuous beside the ambulacral furrows and around the base of 

 the anal tube, which is about as long as half the diameter of the 

 disc, or longer. The oral surface of arms and pinnules seem to be 

 free from plates. Colour of skeleton, very light brown ; of soft 

 parts and sacculi, very dark brown ; terminal half of cirri with 

 more or fewer of the joints marked dorsally, or strongly tinged 

 with pui'ple. 



Twenty-three specimens from Station 28. Off Manning River,. 

 22 fathoms ; fine grey sand. 



All of the individuals of this species were found tightly cling- 

 ing by their cirri to the pinnules and cirri of the larger specimens 

 of Pt. macronema, of which species they were, at first, supposed 

 to be the young. One specimen of macronema carried no less 

 than seven individuals. While it is quite possible that the 

 entanglement took place in the dredge, the appearance of the 

 specimens indicates that the smaller species lives symbiotically 

 with the larger. Mr. A. H. Clark^ has reported a somewhat 

 similar association of a Ileliometra [H. hrachymera, A.H.C.) with 

 a much larger species (^H. eschrichlii maxima, A.H.C) of the same 

 genus in the Sea of Japan. More remarkable than this associa- 

 tion with macronema is the fact that all the larger specimens of 

 pcedophora carry pentacrinoid larvae attached to their pinnules ; 

 the type-specimen bore no less than twenty-four such young. 

 The youngest stage observed (PI. xlvii., fig. 7) has a shorty rather 

 fleshy stalk, with a large attaching disc at one end, and the some- 

 what ellipsoidal body at the other ; at this stage the joints of the 

 stalk appear as more or less discoidal plates, while the body-wall 



T Clark— Proc. U. S. Nat. Mus., xxxiii., 1907, p. 76. 



