A MONOGRAPH OF THE EXISTING CRINOIDS 495 



subject the material from Amboina and from Mortlock Island at Gottiugen to renewed 

 minute and detailed comparison. Hartlaub said that the five specimens from Am- 

 boina, described in 1890 as Antedon amboinensis, differ from the type specimen of 

 brevicuneata at Leyden in the smaller number of arms and especially in the absence 

 of any flattening on the outer sides of the postradial series. He remarked that this 

 character, so striking in a species of the Palmata group, is therefore not to be consid- 

 ered as a constant character of the species. He found the same character very strongly 

 marked in a number of specimens from Alortlock Island. 



In respect to the number of arms six on each postradial series the specimens 

 from Amboina do not resemble Carpenter's type, which has eight arms on each post- 

 radial series, but instead resemble Antedon similis. Carpenter separated similis 

 "with some hesitation" from brevicuneata, with which it shares the lateral flattening 

 of the postradial series. The specimens from Mortlock Island are intermediate 

 between the two forms. They have six arms on each postradial series, as is charac- 

 teristic of similis, and entirely visible IBri, a feature by which, according to Carpenter, 

 brevicuneata is separated from the other forms. In the relative length of Pi, which 

 Carpenter likewise considered as of importance in differentiating the two forms, the 

 specimens studied by Hartlaub showed the relationship supposedly characteristic of 

 brevicuneata, in which P 4 is markedly smaller than P 3 , and P 3 is as long as P. But 

 P 2 not rarely measures 15 mm. hi length, so that Carpenter was hi error when he said 

 that bremcuneata in general has shorter lower pinnules than similis in which, according 

 to him, P 2 is 14 mm. long. The difference between brevicuneata and similis, if con- 

 stant, would be limited to the relative length of P 4 . 



Five specimens from Arnboina identified as Antedon imparipinna, under which 

 form he included Antedon protecta as a synonym, were described by Hartlaub in 1891 

 as follows: The centrodorsal is sometimes a disk of moderate size with a small irregu- 

 larly shaped free dorsal pole marked with pits and bearing the cirri on its somewhat 

 sloping sides, and sometimes a thick disk with vertical sides and a broader flat or 

 slightly concave smooth dorsal pole with a diameter up to 5 mm. The cirri are 

 arranged in two, or two and a partial third, rows. The cirri are XXV-XLVI, 22-25. 

 The segments are tolerably uniform. The three first segments are a little broader 

 than long, the sixth-tenth (in the specimen from Ovalau the fourth-ninth) are some- 

 what longer than broad, and the remainder are again short and are laterally com- 

 pressed. The outermost segments may be somewhat carinate and bear a dorsal 

 tubercle or even a blunt spine. The opposing spine is usually only very feebly de- 

 veloped. The radials are either entirely concealed, or are only visible in small part 

 in the interradial angles of the calyx. The IBrj are short, occasionally entirely free 

 laterally, but usually more or less united laterally. They are as long as the two free 

 sides of the pentagonal axillaries. The postradial series diverge only slightly, some- 

 tunes being in close lateral contact. They divide three times. The IIBr and IIIBr 

 series are 2. As a rule there are no IVBr series. Slight synarthrial tubercles are 

 present. The two ossicles immediately folio whig each axillary are more or less 

 united with each other, the IIBr, often only in the proximal half. The outer borders 

 of the postradial series are notched at the articulations. 



Rarely more than 40 arms, usually about 40. Occasionally one or two of the 

 arms arise directly from the IBr axillary. The arms are 70 mm. long and smooth. 



