46 SMITHSONIAN INSTITUTION 



trophy toward such a singular result, is to be found among the Recent crinoids. 

 In Comatulella brachiolata (Lamarck), the delicate, regular pinnules alternate 

 with others which are much stouter, without any ventral grooves and wholly 

 unconnected with the ambulacral groove of the arm; they are composed of 

 circular segments which are solid except for a minute central perforation. 

 Mr. Austin H. Clark has figured a specimen of this rare species in Ergebnisse 

 der Hamburger sudwest-australischen Forschungsreise (Supplement, 19 13, 

 pi. 4, figs, i, 2) ; and in the Records of the Western Australian Museum 

 (vol. 1, 1915, p. 117) he has given a full description based upon another fine 

 specimen not yet figured. Speaking of the ungrooved pinnules he says (p. 1 18) : 

 At first they lie horizontally, but in the distal half or third they curve dorsally into 

 the form of a hook or spiral, exactly as do the cirri, forming' tendril-like attachments all 

 along the arm whereby the animal fixes each arm securely to the organisms on the sea 

 floor in addition to fixing its central portion by means of its cirri. [And he adds on p. 119] 

 It is most instructive to see that in this specimen the ungrooved pinnules have approached 

 so closely to the cirri in structure that they have taken upon themselves the performance 

 of exactly the same functions. 



In like manner the tubes of such a form as Gilbertsocrimis typus, while 

 occupying the position of proximal pinnules, may be considered as representing 

 enormously enlarged cirri. 



While, therefore, the suggestion of Wachsmuth and Springer as to the 

 probable derivation of the so-called " respiratory pores " from pinnules is con- 

 firmed, it is also true that these pinnules may have possessed respiratory 

 functions, since the proximal pinnules in many Recent crinoids are shown to 

 be lacking the usual functions of pinnules. 



2. SCYPHOCRINUS SPINIFER n. Sp. 

 Plate IX, figs, la-c 



Calyx narrowly elongate, widest about arm-bases; height to width about 

 as 4:3. Plates sharply sculptured, with conspicuous ridges traversing the plates 

 continuously from center to center, diminishing in number from five at the base 

 to one at the first axillary; these meet at the centers of the plates in small 

 elevations surmounted by long spines which frequently fork. Radial series 

 slightly elevated; median ridge of secundibrachs sharp and narrow. Secundi- 

 brachs 12 or 13. 



Height of the only specimen, 40 mm. ; width about level of arm-bases, 

 30 mm. Length of spines, 5 to 7 mm. ; thickness at base, about 1 mm. 



The remarkable character of this species is the spines which are entirely 

 different from the small pustulose elevations seen on specimens of S. pratteni; 

 they are relatively long, and slender at the base, many of them enlarging 

 distally and often forking, while others taper to a point. They occur on the 

 radial series to about the fourth secundibrach, and upon the interbrachials 



