The Ceinoids from Dr. S. Bock's Expedition to Japan 1 9 14. 175 



7 (1 + 2, 4 + 5) 4 cases: 12 mm. II Br— s 7 (3 + 4) 3 cases, 9 (3 + 4) 

 2 cases, II (3 + 4 : 2; 2 + 2 : 1) 3 cases; 9—13 mm. Ill Br— s 9 

 (3+4) 1 case, 11 (3 + 4) 3 cases, 12: I case, 13 (3 + 4) 5 cases, 15 

 (3 + 4) 3 cases, 17 (3 + 4) 1 case, 19 (3 + 4) 2 eases; 9 — 17 mm. 

 IV Br— s 15 (3 + 4) 4 cases, 16 (4 + 5, 10+11) 1 case, 17 (3 + 4) 2 

 cases, 19 (3 + 4) I case, 21 (3 + 4) 1 case, 23 (3 + 4) 1 case, 25 

 (3 + 4) 1 case, 27 (3 + 4) 1 case; 14—24 mm. V Br-s 15: 1, 17: 1, 

 19: 2 cases (syzygy between 3 + 4); 15— 19 mm. Arms partly broken, 

 in a complete specimen probably about LX: total L 105 mm. Un- 

 branched arms 60 mm.: 10 — 20 mm. with rudimentary p — s. The 

 number of the segments of the p -s at the transition II, 11, 9. S, 7, 

 4, 3, 2, 2. Syzygies with an interval of about 20 oblique articulations. 



Pj (to the right on I Br 2 in 3 cases) 16 — 17; 12 mm., Pg 15; 

 9 mm., Pj,, 14; 8 mm. 



Disk 13 mm. Anal cone 4,5 mm. 



The present material of M. interreptus forms an extraordinarily 

 fine and interesting series. Sj). 16 may be the youngest known stage 

 of recent pentacrinoids' or at least of the genus M.etacrinus. 



As to the thickness-growth of the stem one can observe that 

 the increase is most rapid among the young specimens and generally 

 decreases with growing age. When the diameter of the stem is less than 

 1 mm. the stem thickens with 0,i mm. for a length-growth of about 

 15 mm. From l,o — 2,.5 mm. generally the same enlargement of the dia- 

 meter of the stem is reached with an length-growth of 25 mm. (An 

 exception is, however, Sp. 13, but one must notice that the preserved 

 part of the stem is relatively short and the whole thickness-growth 

 only 0,1 mm.: the divergence might therefore be ascribed to errors of 

 measurement.) From 2,.^ — 3,o mm. the diameter of the stem increases 

 with 0,1 mm. on 30 — 35 mm. Between 3,o and 4,o mm. the same growth 

 takes place on 60 — 120 nun. and over 4,o mm. an. equivalent thick- 

 ening is attained on a length-growth of about 80 mm. Exceptions are 

 Sp. 11 with a thick stem, but rapid growth (0,i mm. pro 33 mm.) and 

 Sp. 21, where the diameter of the stem is proximally decreasing. A 



* A figure of a very young specimen of Liocrinus decorus of about the same size 

 is also presented by A H. Clark in 19Ü8 (Proc. U. S. Nat. Mus. Vol. 35, p. 88; a stem frag- 

 ment) and in 1915 (Monograph p. 205; the same stem, here the figure is correctly placed) 

 and by H. L. Clark in 1018 (Bull. Lab, Nat. Hist. Iowa Vol. 7, Rep. Crin .*.• Ecliin. of the 

 Bahama Exp.). 



