PART 5 A MONOGRAPH OF THE EXISTING CRESTOIDS 791 



The radials are short, and are only partially visible beyond the rim of the 

 centrodorsal. 



The 5 arms, which are much elongated and taper very gradually, reach a length 

 of 120 mm. The first brachials are short, very much broader than long, thickened 

 on the edges. The second and third brachials are longer, though still much broader 

 than long; the second is broadened in the distal and the third in the proximal portion. 

 The brachials following the fifth are obliquely wedge-shaped. 



Syzygies occur between brachials 4 + 5 and 9 + 10, and distally at intervals of from 

 3 to 7 (usually from 4 to 6) muscular articulations. 



The lowest pinnule is on the fifth brachial. The earliest pinnules are subequal and 

 are composed of 14 or 15 segments, of which about 7 of the basal, which correspond 

 to the ovarian region, are more broadened than those following, which are more slender. 

 The following pinnules, beyond the tenth to twelfth, are longer with the third segment 

 elongated and those following still more elongated ; these pinnules equal or even exceed 

 7 brachials in length; the genital region always reaches to about the seventh segment. 

 The ends of the pinnule segments are perceptibly swollen, and even bear 2 or 3 very 

 fine spinules. 



The perisome of the disk, which reaches a maximum of about 6 mm. in diameter, 

 and of the interbrachial areas is very thickly set with small regular calcareous plates 

 as described by Carpenter in P. semperi. 



Sacculi are present in the form of excessively fine granules which are whitish in 

 color and contrast sharply with the more or less dark tissue which surrounds them. 

 They are extremely numerous and crowded on the disk, as well as on the perisome 

 of the earlier brachials, but their number decreases rapidly and they soon become 

 scarce. 



Notes. Of the 3 specimens dredged by the Princesse- Alice, the largest, with the 

 disk 6 mm. in diameter, was from station 1118; the most perfect was from station 578 

 and was somewhat smaller, the disk being about 5 mm. in diameter; an arm fragment 

 measured about 80 mm.; the example from station 486 was very small, the disk measur- 

 ing only 3 mm. in diameter. 



Prof. Koehlcr compared these specimens directly with Perrier's types at the Paris 

 Museum and found them to be unquestionably of the same species. 



In one of the Talisman examples recorded by Perrier which still retains a few 

 complete cirri, Koehler counted 16 or 17 cirrus segments; the longest of these cirri did 

 not reach 35 mm. in length. Since some of the arm fragments measured 80 mm., the 

 arms must be more than twice the length of the cirri. 



Koehler noted that the figure of this species given by Perrier in 1886 (republished in 

 a second edition of the same work in 1891) does not give a correct idea of the relative 

 proportions of the arms and cirri. 



In the specimen from Princesse-Alice station 486, Prof. Koehler found the arrange- 

 ment of the syzygies to be as follows: First arm, between brachials 4+5, 9+10, 14 + 15; 

 second arm, between brachials 4 + 5, 9+10, 15 + 16, 18+-19, 22+23, 27+28, 31 + 32; 

 third arm, between brachials 4 + 5, 9 + 10, 16 + 17, 19+20, 23+24, 27 + 28; fourth 

 arm, between brachials 4+5, 9 + 10, 15 + 16; fifth arm, between brachials 4+5, 9+10, 

 14+15, 18 + 19. 



