160 BULLETIN OF THE 



Actinometra pulcheUa PocKTAiiis sp. 



Cirrhi 15-20, of 15-18 joints ; the fourth or fifth is the longest, and the fol- 

 lowing ones gradually develop a blunt spine on the dorsal side. Two radiahi 

 only visible ; the axillary short, wide, and almost triangular. 10-20 anus, 

 most of the rays usually dividing twice, the first division (distichals) consisting 

 of two joints which are not united by syzygy. When the arms spring directly 

 from the radial axillary, the two lowest brachials are united by ligament, as in 

 most Comatulce, and the third is a syzygial or double joint. But in all the 

 arms which spring from a distichal axillary, the two lowest brachials are united 

 by syzygy to form a double joint ; and the true third brachial, which is also a 

 syzygial joint, as in all Comatulce, thus becomes the second arm-joint, as in Act. 

 Solaris.* The position of the next syzygy may be anywhere between the 12th 

 and 20th joints, after which there are usually intervals of three or four joints 

 between the successive syzygia. The lower arm joints are sharply wedge- 

 shaped, alternating from side to side, the later ones gradually becoming blunter. 

 In some specimens the dorsal surface of the arms is unusually smooth, the 

 joints not overlapping in the slightest degree ; but in others the lower parts of 

 the arms, about as far as the 25th joint, are exceedingly rough. The distal 

 edge of each joint is raised on the side next the pinnule into a high, somewhat 

 recurved plate, with more or less serrated edges. This is largest about the 

 15th joint and gradually decreases in prominence, the joints after the middle of 

 the arm being quite smooth, f The arms of most individuals, whether rough 

 or smooth, are bordered throughout their whole length by a lateral expansion of 

 the ventral perisome, which embraces the lowest joints of the pinnules.! The 

 first pinnules of the arms are rather long, with well-marked terminal combs. 

 The length gradually decreases till about the 10th brachial, and then begins to 

 increase, but there is no specially small pinnule. The terminal comb may 

 continue as far as the 10th brachial, or cease four or five joints sooner. The 

 pinnule joints may be almost smooth, or they may have strong projections to- 

 wards the dorsal side, even to far out on the arms. 



* This peculiarity is a very marked one. In no case have I found a syzygy in 

 the first joint of any arm springing from a radial axillary. The ten-armed forms 

 thus belong to the type of Act. m . But individuals with 12, 13, 16, 



anus are by no means care, and tarnish a complete transition to the large examples 

 with 20 arms to which the specific designation (pulcheUa) by Pourtales is strikingly 

 applicable. 



t This character is especially distinct in the ./„/. alata of Pourtales from Bar- 

 and in several specimens, l»>th ten- and twenty-armed, from Station 2i 

 Vincent). In other individuals from this station, as in these named .////. pulcheUa 

 (Pourtales), the arms are perfectly smooth throughout their whole length. 



\ This is the character which led Pourtales to give the specific name a 

 tain individuals dredged by the " Hassler" at Barbados, in which it is especially 

 marked. It occurs also, though less distinctly, in the original specimens of Aid. 



pulchella. I find it to he a very variable < , even among the different arms of the 



same individual, some of which arc webbed and others not. 



