12 T. GiSLEN, 



have, however, contrary to my procedure in the Mjobergian work, 

 denoted by Pi( = Pc), Pi,(=Pd), Pm( = Pp) and Piv(=Ppp).' 



In order to demonstrate the ramifications of the arms I ha\"e 

 used the same schemes that I demonstrated in my Mjobergian inves- 

 tigation. In these schemes synarthries are indicated by hyphens, sy- 

 zygies by the plus sign. Though synartries and syzygies have diffe- 

 rent marlis they can. however, in certain species pass over to each 

 other to an unlimited extent and in such dubious cases I have often put 

 a query instead of one of the above-mentioned marks. The »pseudo-» 

 syzygy when fully developed is denoted as a »true» syzygy. Roman 

 numerals signify the number of division-series, thus for instance 11 = 11 

 Br, arabic ones = the ordinals of the segments. Br as usual = brachial. 

 R = radial. I have marked the regenerate by adding an index to the 

 number of the segment. The index mark 1 forms the sign of a first 

 regeneration, 2 of a second one and so on. The distribution of the 

 pinnules is indicated by horizontal lines which are applied below or 

 above the symbol of the segment according as the pinnula is fixed in- 

 side or outside the arm. 



The abreviations that I have used are the following: 



B = basal4 br = breadth 



Br = brachial h = height D = Dorsal cirrus whorl 



C = cirrus L = length \' = \'entral cirrus whorl 



Cd = Centrodorsal^ N = number 



IR = interradially S = number of segments 



P = pinnuia_. T = teeth. 



R = radial* 



' For the pronunciation of these symbols I suggest: primi-p., secundi-p., lerli- 

 p. etc. 



