A MONOGRAPH OF THE EXISTING CRINOIDS 237 



The radials are usually even with the rim of the centrodorsal in the rnidradial line 

 and visible as low triangles in the interradial angles. The IBr, are short, slightly over 

 three times as broad as long, with the lateral borders nearly straight and parallel. 

 They are united in the proximal half but are separated in the distal half by a moder- 

 ately broad U-shaped gap. The IBr 2 (axillaries) are broadly pentagonal, twice as 

 broad as long. There are usually 10 IIBr 4(3+4) series present; exceptionally IIBr 

 2 series occur. IIIBr 2 series are sometimes present. The division series are well 

 rounded dorsally and well separated laterally, the sides perfectly smooth with no 

 trace of lateral production. 



The 13-21 (usually 20) arms are 90-150 mm. long in fully developed individuals. 

 The brachials are smooth. 



Syzygies occur between brachials 3+4, again from between brachials 9 + 10 to 

 between brachials 21+22 (usually about brachials 19+20), and distally at intervals 

 of 4-14 muscular articulations. 



P D is stout basally, but tapers rapidly, becoming very slender distally. P, is 

 larger and stouter than P D and tapers less rapidly. P 2 is similar to Pi. P, is some- 

 times large and long, like the pinnules preceding. The lower pinnules are very long 

 but slender and perfectly smooth. 



Notes. — Muller's original description, which was based on the specimens from the 

 Red Sea collected by Hemprich and Ehrenberg, is as follows: The cirri are XXX, 

 24-29; the outermost 12-14 segments bear a process on the dorsal side. The radials 

 are visible. The IIBr series are 4(3+4). In the next division the axillary has no 

 syzygy. The 20 arms are up to 150 mm. in length. The second ossicle beyond the 

 radial (IBr) axillary can be rocked from side to side on the first (which means that 

 there is a synarthry between the first two ossicles beyond the IBr axillary). The 

 brachials are smooth. The intersyzygial interval is 4 to 9 muscular articulations. 

 The first pinnule is on the second segment after either the first or the second arm 

 division. The second and third pinnules are the largest, and sometimes the fourth 

 is also large. The first pinnule is thick basally but tapers rapidly and is not so 

 long as the second. The skin of the disk is soft. The color in alcohol is yellowish 

 brown. Muller gave the size as up to one foot, which would mean an arm length 

 of 150 mm. 



Carpenter examined Muller's specimens in the Berlin Museum, and in his key 

 to the species in the Savignyi group published in the Challenger report (1888) he added 

 some features to those given by Muller. He noted that IIIBr 2 series may or may not 

 be present. There are no lateral processes on the segments of the lower pinnules. 

 The cirri are XXV-XXX, between 25 and 35, and the later cirrus segments have 

 strong spines. The second syzygy is between about brachials 19 + 20. P D is smaller 

 than Pi. 



Hartlaub gave an excellent figure of one of Muller's original specimens, which the 

 museum at Gottingen received in exchange from the Berlin Museum. He noted that 

 this species does not always have as many as 20 arms, and that a second specimen 

 from Muller's material at Gottingen has not more than 13 arms. 



In one of Muller's specimens in the Berlin Museum that I examined the centro- 

 dorsal is discoidal, moderately thick, with a flat dorsal pole 3 mm. in diameter. The 

 cirrus sockets are arranged in two and a partial third alternating marginal rows. The 



