The ("kinoiiis kuom I)k. S. Bock's Kxi'Kdition 'i'o -Iai-ax 1!M4. I I 



ing stetn has given figures from 2 to 2,:. metres. It is, howevei', to 

 be noticed that large forms, such as M. rotundus, probably have stems 

 which during their increase of thickness become a good deal longer. 

 Concerning both the first-mentioned species and the latter ones it is 

 very possible tlial the length-increase of the stem is continued even 

 after the increase of thickness has ceased. A couple of measurements 

 have shown that the thickness of the stem can even decrease proxi- 

 mally, which ought probably to be regarded as a phenomenon of old age. 

 The study of the components of the division-series has led to interes- 

 ting results which will be treated in a special investigation in connection 

 with the question of the new formation and augmentation of the num- 

 ber of arms in the genus Metacrinus and in the discussion of the rela- 

 tion between pinnulae and arms. 



Concerning the terminology I have used the same names as 

 in my work upon the Mjobergian Crinoids, i. e. about the same as 

 Bathee, a. H. Claek etc. have employed. 



Thus R (the radial) is the first ossicle of the arm. The ossicles 

 between the )-adial und the first arm-ramification are denoted as primi- 

 brachials I, 2, etc. (1 Br 1, I Br 2). The last ossicle before this arm- 

 division is an axillary (1 Brax), carrying on its distal surface two se- 

 condary arms. If the animal has only X arms there are no further 

 arm-ramifications, otherwise after the I Brax the secundibraehials (II 

 Br:s) follow with the 2 nd, 4 th or, among the stalked crinoids, even a 

 more distal segment forming an axillary. On this a new division-series, 

 the tertibrachial (III Br), may possibly arise, then pei'haps a IV^ Br 

 sci'ies and so on. The segments of the arm-branches that are not 

 further divided ai'e signified as brachials (Br) with the number of the 

 segments counted from the last axillary. 



The number of the Ciri'i (C) as well as of the arms is written 

 in roman figures, the number of the segments in arable ones. By the 

 word »whorl» in the description of cirri I mean their arrangement in 

 a horizontal line, but I speak of »row» when referring to theii- arrange- 

 ement in a vertical line. 



The jiinnules (P) are denoted on the outside of the ai'm by 

 ordinals, on the inside they are indicated by letters (a. b. e). 1 Br (Cos- 

 tal). II Hi- (Distical). HI Br (Palmar), and 1\' Br (poslpalinarl pinnules I 



