KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 25. N:() 2. 47 



BB somewhat irregular in shape, owing to the disturbance of symmetry by the anal 

 plates: this feature is more marked in the British Museum specimen No. 47,859. They 

 are pentagonal, but the left upper side of eaeh plate is usually longer than the right 

 upper side, so that in eaeh radius the basa] tends to assume a radial position. 



KK. ( >wing to the minuteness of the cup and the dimeulty of dissecting it ont, it 

 is härd to say how niany of thera are compound. The 1. post. R. appears to be single, 

 while all the others inay have been conipound. The inferradials are irregularly- penta- 

 gonal: R', which is far wider tlian the others, is hexagonal and Supports x and r. post. R s . 

 The superradials are ronghly quadrangular and not easily distinguishahle from the primi- 

 brachs, which they support by their entire upper surfaees. 



Anns: thpse visible in a are the right and left posterior and small portions of others. 

 In both these there are 7 primibracåis. In r. post. arta, IBi^ and IBr 2 are broad and 

 abut against the lower plates of the tube; IP)]*., is broken, otherwise its sides would slope 

 inwards; the four succeeding primibrachs are mueh narrower, being about half the width 

 of IBr,. In the 1. post. arm IBr :5 slopes inwards in the same manner. The rapid thinning 

 of the arms at this point is also shown in Mr. Holliers specimen, and was mentioned 

 by Angelin in his diagnosis of the genus: it is, however, a eommon character of the 

 Heterocrinidae. The joints between the braehials are sinuous, especially in the proximal 

 region (fig. 38) where there is a groove on the upper surface of eaeh brachial: this may 

 be connected with the coiling of the arms in the plane of the stem. 



The r. post. arm bears 5 secundibrachs in either series, but, as the öth in eaeh is 

 broken, there may have been more. The remaining braehials of this arm are not pre- 

 aerved. The 1. post. arm also has 5 secundibrachs in either series; subsequently the arm 

 continues as two main branches which give off finer branches on the inner side. These 

 artidets are given off at interyals of 5 or 6 ossicles; they are about half the width of the 

 main arm, extend to ;i eonsiderable length and do not appear to branch again. 



Anal struetures: The lower plates of the ventral tube are wide, like the arm- 

 plates on which they abut, but the} - are only three-quarters their height. Like the arms 

 the tube narrows on the ord and 4th plates, and continues as a long narrow series of 

 plates which can hardly be distinguished from the arm-ossicles. They remain throughout 

 about as wide as IBr 3 is in its middle region. The tube extends to the distal end of the 

 speciinen without lessening in diameter; it was no doubt as long as the arms and perhaps 

 longer. There are preserved in specimen a 28 plates of the vertical series, with a total 

 length of 24 mm., to which 1 mm. may be added to allow for curvature; the normal 

 height of the plates is about 1 mm. 



Stem: In specimen h the length of stem figured is 24 cm.; all is of course not 

 seen. In specimen c the length of the stem between the crown and the broken distal 

 end was 36 cm.; and in this specimen all the stem is certainly not preserved; 6 cm. at 

 the very least may be added, giving a total length of at least 43 cm. The length of the 

 crown in this specimen was about 35 mm.; we sliall therefore be on the safe side in 

 saying that the proportion of stem to crown in this species was as 10 to 1. 



The six regions into which the stem of this species may be divided have already 

 been described in general tenns. In region 1 the diameter is 1.25 mm.; the ossicles are 



