III 



TORSTEN GISLEN, CRTNOIDS. 



| Bil, -2, 3, +4,. . 



I Br 1, -2. 3, + 4. . . . No distinct syzygies on account of tlio voutli of tlic 

 il I -2 3 !- I, , 



| Brl, — 2,3, + 4, . . . regenerated arms. 



Ilf 1.-2. 



| Br 1,-2, 3,-1-4,. . . 



Kl fBr 1-23+45. . .39+40. . -58 + 5'J 



| IV 1-2 3+4 



III 1-2 I Br 1-23 + 45. . -37 + 38. . .59 + 00 



I Br 1-2 3+4 5 53 + 54 



f Br 1-2 3 + 4 5 40 + 41. . .03 + 64 



III 1-23 + 4 { 



l Br 1-23 + 45 38 + 39. . .59 + 60 



{ II 1-2 3 + 4 



73 + 74 . . . 

 70 + 77 . . . 



74 + 75 . . . 



. . . 87 + 8S 

 70+77 . • • 



The division series and the Br:s up to about Br 10 markedly smooth, discoidal, 

 t hen inore or less wedge-shaped with produced distal borders. For the distribution 

 of the syzygies see the scheme. The only exception to this distribution of syzygies 

 is an arm that comes directly from a II Br 2. The appearance of syzygies is here: 

 1-23 + 4 . . . 13 + 14 . . . 19 + 20 . . . 25 + 26 . . . 33 + 34 . . . 42 + 43 ... Is this 

 possibly a phenomenon resembling the one observed in Comaslcr midtifida juv. Per- 

 haps it is a general phenomenon that young arms have closer syzygies. 



The pinnulation of tlie arms is indicated in the scheme in the same may as in 

 the one under Comaster typica. 



P x 31—39, 14 mm; P 2 32^36, 16 mm; P 3 19 — 28, 9—12 mm; P 4 18 + , about 

 8 mm; P 5 13, P 13, 6 mm. The P:s then again increasing P JL 19, 9 mm. — P a 

 about 25, 13 mm; P b of similar length; P c and P d rapidly decreasing. P f the shortest; 

 then the P:s increasing again. 



Disk thrown off. 



Colour in spirit: The arms påle chocolate brown. The pinnules dark violet, 

 white ribboned. Cd see above. The soft parts of the animal dark coloured. 



The species last described is undoubtedly mostclosely related to Zygomelra elegans 

 Bell. This species is distinguished from Z. microdiscus by having »mostly or entirelv 

 (Clark op. cit. 32, p. 734) two ossicles in the III Br series in stead of 4 (or 3 according 

 to the older terminology). Bell characterizes the species as follows (Alert» pag. 162): 

 »...three distichals . . . If the arms divide again there are generally two joints, 

 when there is not a syzygy; but there may be three joints and then the axillarv 

 is a zyzygy » (2IIIBr:s in 4 cases, 4 III Br:s in one case, according to the figure). 

 P. H. Carpenter (Chall. Rep., Vol. 26, p. 94) says: Palmars and postpalmars (when 

 present) usually of two-articulated joints.» 



A. H. Clark in op. cit. 31, p. 459, has referred a specimen to this species 

 and in a note he gives the following statement: >. . . eleven of the III Br-series are 

 2 and seven are 4(3 + 4)...» In my specimen there are 2 III Br:s in 14 cases, 4 in 

 one case. In the specimen first described (a microdiscus s. str.) there are 2 III Br:s 

 in 7 cases, 4 in 11 cases. 



The boundary between the two »species» is evidently rather vague. To which 

 species should one refer a specimen which has the same number of two- and four- 

 jointed III Br:s? 



