28 RHIZOCRINUS RAWSONII. 



The cup is proportionally more elongated than in the other species. It is 

 composed of five rather long basals and the rather short first radials {Fig. 4). 

 These ten pieces are solidly connected, bnt the joints are always plainly 

 visible with a lens of moderate power, as they are also in K. lofotensis. The 

 second radial is short and nearly square {Figs. 4, 5). The third is largest and 

 somewhat broader at its distal end. The four first brachials are equal in 

 size to the radials, square, broad, flattened out at the sides, and apparently 

 united in pairs by syzygial joints {Fig. 7). They contribute with the radials 

 in forming the supports of the visceral cavity ; the peristome being on the 

 same level with and attached to the distal end of the fourth brachial 

 {Figs. 1, 7), whilst in R. lofotensis it is fastened to the third radial. There is in 

 no part of the arm a sudden narrowing down, as in the first brachial of R. 

 lofotensis represented in Fig. s. The first pinnule arises from the fourth bra- 

 chial. The arm-joints are very short, broader than long, every other joint 

 being a syzygium. They are not as deeply emarginated for the insertion of 

 the pinnules as in the other species {Fig. 7). 



There are from fourteen to twenty-two pinnules {Figs. 9-12) a side on each 

 arm, the two first joints of which are considerably larger than the following, 

 which decrease regularl}'^ in size to the tip ; the lateral scales are much 

 smaller than in the other species, where they are largest in the middle of the 

 pinnule, thus giving it a long lanceolate appearance {Fig. 13). 



The mouth is central, somewhat elongated in a direction at right angles 

 with the diameter passing through the anus. The angles of the mouth are 

 provided with hard lanceolate papilla^ as in the species described by Sars. 

 The anus is large, more oval than round, and somewhat bulging without 

 being tubular {Fig. ij^). 



The largest specimen obtained measures 17 c. m. in height without the 

 arms, and was originally longer, since the root is wanting. The diameter of 

 the stem is 1.5 to 2.0 mm. It is composed of sixty-three joints. 



The color is whitish and the surface clean. The skin I mentioned in the 

 description of R. lofotensis (under the name of Bourgueticrinus Hotessieri) in 

 No. 7 of the Bulletin of the Museum of Comparative Zoology, I have since 

 found on closer examination to be a parasitic growth of a hydroid polyp. 



I have mentioned above that the solid part of the cup or calice is formed 

 by the union of the basals and first radials. Sars, in his description of Rhizo- 

 crinus lofotensis, strangely enough considers the lower portion as formed by 

 an enlarged joint of the stem, in the same manner as in some of the fossil 



