The Crinoids from Dr. S. Bock's Expedition to Japan 1914. I(i:{ 



faces of the nodal joint in M. rohmdus (PI. 52, fig. 8, not as stated 

 in the desci-iption fig. 2) and in the debated stem-fragment (PI. 52, fig. 

 15). According to the description this face in M. Steivarli (p. 444) is 

 »quite different from the circular syzygial surface in M. rotundus (PI. 

 LII. fig. 3) and resembles that of M. interruptus. The syzygial surface 

 of the nodal joint, however, is somewhat lobate as in the Vega-spe- 

 cimen». It appears from the figures that this stem very much resem- 

 bles that of the above-described Sp. 7, which has more angular inter- 

 nodal joints with stronger ring-ridges than the typical M. rotundus. 

 The importance that Carpenter attached to the appearance of the nod- 

 als and internodals has proved to be a little exaggerated and to some 

 extent is subject to individual variation as well as the tubercles and 

 ridges on the sides of the segments. At first I supposed that M. Stew- 

 arli ought to be considered a variety of M. rohmdus and referred to 

 Sp. 7 here. By a comparison of the different stems in the collection 

 I become, however, convinced that one ought not to separate M. Stew- 

 arti even as a variety. With regard to appearance and formation of 

 ridges and tubercles the most distal part of the stem in Sp. 2 agrees 

 completely with Sp. 7, on the other hand the IP'' — 17"' internodes are 

 rounded, without radial ridges or corner-tubercles and therefore of the 

 usual M. rohindus-tyi^e. S2>. 3 has indistinct ring-ridges and sharply 

 pentagonal segments in the 10"' — 16*'' internodes, but in the most distal 

 internodes rounded segments without ridges again. 



H. L. Clark in 1910 described a new species most closely related 

 to M. rotundus as M. cyaneus. (Commonwealth of Austral. Fisheries 

 Vol. 4, part. 1 p. 9). The Radiais in this species are usually 6(1 + 

 2, 4 + 5) but often 7 (1 + 2, 4 + 5); P^ 20 mm. < P^ < P3; P4 25 mm. 

 = P5, Pß shorter; the Br-s a little overlapping in the middle of the arm, 

 the longest cirri with 60 — 64 cirrals, internodals 7 — 15 (usually 9 — 14). 

 These are the most important features that the author gives to charac- 

 terize tlie species. The only real differences between my specimens 

 of M. rotundus and M. cyaneus are the number of cirrals and radiais. 

 The number of internodals are about the same in both species, the 

 arms are in M. rotundus (the type) »tolerably smooth», in my specimens 

 a little serrate in lateral profile, in M. cyaneus »the brachials have some- 

 what flai'ing distal margins . . becoming smooth near the armtip.» The L 



