A MONOGRAPH OF THE EXISTING CRINOIDS 477 



dorsal is small, markedly stellate, without any trace of cirri or of cirrus sockets. The 

 disk is over 35 mm. in diameter. The mouth is interradial. 



The specimen from the Percy Islands, Queensland, has 63 arms which are from 

 85 to 90 mm. long. A single cirrus with 15 segments remains. The interradial dorsal 

 perisomic plating is very heavy, the plates being exceptionally thick and convex 

 dorsally. The 5 lowermost plates stand out large and prominent in the interradial 

 angles, being especially convex dorsally. 



The specimen from New Britain has XIII stout cirri about the edge of the centro- 

 dorsal. 



The example from St. Matthias Island is small, but without cirri. 



The specimen from the Solomon Islands is large. 



The specimen from Mortlock Island is small but typical. It has 52 arms which 

 are about 85 mm. long. On 4 of the rays the IIIBr series are 2 externally and 4 

 (3 + 4) internally. On the fifth ray one of the external IIIBr series is 4 (3 + 4) instead 

 of 2. The cirri are VIII, 13-14. 



The specimens from Albatross stations 5249 and 5250 and one of those from sta- 

 tion 5254 have each 2 well-developed cirri. 



Carpenter said that the specimen from Challenger station 208, which is the type of 

 his Actinometra nobilis, is more uniformly colored than the 5 from Zamboanga and 

 has a much larger terminal comb, which extends to the fortieth brachial instead of 

 ceasing at about the tenth as in the Zamboanga form. I did not see this specimen at 

 the British Museum. 



The 5 specimens from Zamboanga were originally considered by Carpenter as 

 representing a distinct species, which he mentioned in 1884 as Actinometra dissimilis, 

 but in 1888 he incorporated their characters in his description of Actinometra nobilis. 



Of this form he says that the centrodorsal is a thin disk, in the adult more or less 

 stellate and rather below the level of the radial pentagon, in immature individuals with 

 about X marginal cirri. 



The 2 elements of the IBr series are short and are closely united laterally. The 

 rays may divide five times. The IIBr series are 4 (3+4). The IIIBr series are 2 

 exteriorly and 4 (3 + 4) interiorly. The IVBr and VBr series are 4 (3 + 4). The 

 first 2 elements of the IIBr series of each ray are closely united laterally; those of 

 adjacent rays are sometimes united all around the calyx, and sometimes separated 

 by a strong interradial plating which extends to about the level of the IIIBr axillaries. 



The 80-100 arms are 150 mm. in length. The anterior arms are long and slowly 

 tapering and are composed of from 150 to 200 slightly overlapping brachials which 

 remain almost triangular until near the end. The posterior arms taper rapidly and 

 are composed of from 80 to 100 or more quadrate brachials. 



Syzygies occur between brachials 3 + 4, again from between brachials 11 + 12 to 

 between brachials 18+19, and distally at intervals of from 4 to 6 muscular articu- 

 lations. 



PD is moderately stout, reaching 30 mm. in length. Those on the succeeding 

 division series gradually decrease in size, but P] is only half as long as its predecessor, 

 and the next 2 pairs of pinnules are not much smaller. The terminal pinnules are 

 much longer in the anterior than in the posterior arms. The terminal comb of the 



