PART 5 



A MONOGRAPH OF THE EXISTING CRIXOIDS 437 



Of the 66 specimens in the collection of the Australasian Antarctic Expedition 

 (Aurora), 53 have 10 rays and 20 arms; 2 have 10 rays and 22 arms, IIBr series l>cing 

 present; 4 have 9 rays and 18 arms; 4 have 8 rays and 1(5 arms; and 3 have 6 rays and 

 12 arms. 



Of the 20 specimens from the Swedish South Polar Expedition (Antarctic) , 17 have 10 

 rays and 20 arms; one has 10 rays and 23 arms; one has 10 rays and 19 arms; and one 

 has 9 rays and 18 arms. 



Of the 15 specimens from the collection of the German South Polar Expedition 

 (Gauss), 1 have 10 rays and 20 arms, and 8 have 6 rays and 12 arms. The specimen 

 with 10 arms proved to be Florometra mawsoni. 



The Terra Nova Expedition also yielded a 12-armed specimen. 



The Discovery Investigations obtained a total of 163 specimens, of which 28 have 

 less than 20 arms and one has more. This last has 11 radials and 22 arms. There 

 were 16 specimens from the Bransfield Strait area with 18 arms and five others \\itli 

 from 16 to 19 arms. Twenty-two specimens with the normal 20 arms were taken with 

 them in that area, which, Dr. John says, are much younger and smaller than those with 

 abnormal numbers of arms; their longest cirri consist of 25 to 38, mostly 30, segments; 

 those of most of the specimens with 16 to 19 arms are of 50 to 65 segments. Five of 

 the six specimens with abnormal numbers of arms from the Graham Land region are of 

 medium size, their longest cirri of 39 to 45 segments; one is small, its longest cirrus of 

 28 segments. 



In the 19-armed Discovery Investigations specimen from the Graham Land region, 

 the single arm arises from a normal radial which is followed by a regular ossicle slightly 

 longer than the IBr! (costals) of the other rays. Next comes a still longer ossicle with 

 a pinnule arising from either side of it. It is succeeded by a syzygial pair with a pinnule 

 arising from the epizygal and beyond this the arm is normal. The single arms of the 19- 

 and 17-armed specimens from the Bransfield Strait are different. The second ossicle be- 

 yond the radial is shaped like an irregular axillary, and a pinnule arises from one side 

 of it. It is followed by a very short ossicle with no pinnules, which appears to corre- 

 spond with the first brachial of normal arms; after it, comes a longer ossicle shaped like 

 the second brachial of normal arms, with a pinnule on the opposite side to the first. 

 A syzygial pair with the pinnule arising from the epizygal, on the same side of the arm 

 as the first pinnule, comes next and thereafter the arm is normal. 



The B.A.N.Z.A.R.E. collection included 43 out of a total of 183 Antarctic specimens, 

 with other numbers of arms than 20. One specimen has 22 arms arising from 

 1 1 radials. Dr. John writes that the 1 1 specimens with 18 arms are all large. Twenty- 

 seven specimens with only 12 arms are all of medium or small size; but they have 

 the same arm length; the ossicles are heavier, the axillaries and second brachials are 

 elongated, and there are strong synarthrial tubercles. These are signs of age, and 

 are to be seen in the larger of the normal 20-armed specimens from the Antarctic; the 

 smaller have short, wide axillaries and first brachials, and no synarthrial tubercles. 

 In the youngest specimens the interradial rays are smaller than the radial. The nine- 

 teen specimens from Kerguelen in this collection all have 20. arms. 



The U.S. Navy Antarctic Expedition of 1947^8 collected one specimen from off 

 the Knox Coast, 110 E. on the Antarctic continent, with 6 rays and 12 arms, 150 

 mm. long. 



