ACTlNOMETfU TYPICA. 



19^ 



ticulation while .still retaining its syzygial character. Loven 

 has given a diagram of it as an articular face in J'hano- 

 genia {Act. typica) , and I have studied it in a much mu- 

 tilated specimen dredged by the » Challenger" in the neigh- 

 bourhood of the Fiji Islands. The only reason for calling it 

 an articulation is the presence of the median vertical line , 

 which can hardly be called a ridge , dividing the face into 

 two parts. But Loven figures a similar ridge on the »iac- 

 ies syzygii brachialis 1 — 2 rami tertii" which is an un- 

 doubted syzygy ^) with radiating striae reaching the dorsal 

 margin. I find traces of a similar median line on the syzy- 

 gial faces of the lower arm-divisions of the » Challenger" 

 specimen, but it gradually disappears and the syzygial faces 

 of the outer arm-joints are of the ordinary character. 



It may be noted here that radiating striae are not nec- 

 essarily characteristic of a syzygy, being absent in Pen- 

 tacrinus and in Rhizocrinus , in which the apposed faces are 

 smooth and devoid of any markings whatever. 



The following are the characters which I believe to be 

 more especially distinctive of Actinometra typica. Loven 

 has already given an admirable detailed description of 

 the type -). 



» Centrodorsal stellate, with few or no cirrhus-sockets , 

 and nearly flush with the radials. Second and third ra- 

 dials united by syzygy, but the junction line is rarely dotted. 

 Rays may divide 7 or 8 times. Primary arms of three disti- 

 chal joints , the axillary a syzygy ■'). Subsequent divisions 

 each of two joints united by syzygy. A syzygy in the first 

 brachials 5 the next usually between the 8tli and 10th brach- 

 ials, and then an interval of two joints between succes- 



1) Loc. cit. p. 230. d. 



2) Loc. cit. pp. 231—333. 



3) According to the usual rule; oue would expect the first and second dis- 

 ticlials (l)oth in this and in the preceding species) to be united by syzygy like 

 the outer radials. Not having seen a joint face I cannot speak positively, but 

 judging from Loven's description (p. 233) 1 think that there may possibly be 

 ii ligamentous articulation in this position. 



Notes from the JLieydeii ÜMuseum, Vol. 111. 



