MONOGRAPH OF THE EXISTING CRINOIDS. 523 



OLTFTOMETRA TUBERO8A. 

 Fig. 1211, pi. 34. 



On January 25, 1875, while in the Philippine Archipelago off Panglao and 

 Siquijor (lat. 9 26' N., long. 123 45' E.) the Challenger dredged in 375 fathoms a 

 single young pentacrinoid, which Carpenter identified as belonging to Glyptometra 

 tuberosa, captured at the same station. 



The total length of the pentacrinoid is 6 mm., of which the column represents 

 about 4.2 mm. 



There are 13 columnals, including the centrodorsal but not the terminal stem 

 plate. Only the centrodorsal and the segment immediately below it are broader 

 than long. The eighth-ninth, which are the longest, are greatly elongated. There 

 are no indications of cirri. 



The calyx is conical and rather narrow, the sides diverging, in approximately 

 a straight line, from the centrodorsal at an angle of about 60. 



The basals and radials are of about the same height, and their lateral borders 

 are united for about the same distance. 



The IBrj and IBr 2 are elongated and very narrow. The IB^ occupies the 

 median third of the radial. There are about six brachials, which carry large 

 and conspicuous covering plates. 



The larva is a trifle more robust than the corresponding stage in Antedon 

 bifida. 



ANTEDON PETA8TTS. 

 Fig. 1355, pi. 56. 



In January, 1910, Doctor Mortensen found attached to a Balanus on a valve 

 of a Pecten maximum at Kristineberg, Fiskebackskil, Sweden, a single pentacrinoid 

 of Antedon petasus. 



The crown of this specimen measures 2 mm. and the column about 4 mm. 

 in length. Both the first pinnules and the cirri are present, having apparently 

 arisen contemporaneously. 



The column consists of 27 segments, of which the 9 proximal are short, and the 

 2 nearest the calyx conspicuously broader than the others. The fully formed 

 columnals are hourglass-shaped, widened at the ends in the usual way, the long 

 axes of the articular surfaces of each at right angles to each other. There is no 

 trace of the median annulus. They are rather short, 0.3 mm. long by 0.1 mm. wide. 

 Distally the columnals become gradually shorter. The terminal stem plate is 

 only slightly lobed. 



There are no infrabasals. This I can confirm personally, for Doctor Mortensen 

 was so kind as to allow me to study the specimen in his laboratory at Copenhagen. 



The calyx exhibits no distinctive characters. 



The orals resemble those of Antedon bifida. 



The first pinnules are on the eleventh or twelfth brachials. 



The cirri are radial in position. 



