352 



VERRILL 



Another striking peculiarity of the Asteriinae of this region, and of 

 the Antarctic Ocean generally, is the large percentage of species that 

 have the skeletal plates, and sometimes the spines, covered with a 

 thick and soft, but rather tough, dermis, which is usually canalicu- 

 lated, and often entirely conceals the plates in alcoholic preparations, 

 or even in dry ones. 1 Even the spines, if small, may be submerged in 

 the dermis, or appear as mere papillae. 



In some cases such starfishes have the skeletal plates, more or less 

 aborted, especially the dorsal ones, but sometimes even the upper 

 marginals, as in Anasterias, Padasterias, and Adelasterias. 



FORCIPULOSA. 



No doubt the most peculiar and remarkable species, pertaining to 

 these southern waters, is the Labidiaster radiosus Liitken, belonging 

 to the Brisingidae. 



It has a small disk with from twenty-six to forty-two rays, the 

 number increasing with age, and grows to a large size. Unlike the 

 other forms of Brisingidae, it lives in shallow water, as well as at a 

 considerable depths. It is found on both coasts of Patagonia and off 

 Cape Horn, etc. 



The only other describe^ species is L. annulatus Sladen. It oc- 

 curred off Kerguelen Island and Heard Island, in 75 to 150 fathoms, 

 and in the Arafura Sea ( ?) in 800 fathoms. It has forty to forty-five 

 long, slender rays. It differs considerably in structure from L. radio- 

 sus, especially in having the dorsal and superomarginal plates nearly 

 abortive distally, on the rays, beyond the genital regions. This last 

 character, with others, should require a generic separation. 



Therefore I propose for it the new generic name, Labidastrella, 

 with L. annulata as its type. 



Aside from Labidiaster, the most characteristic species belong to 

 the Asteriidae and Ganeriidae. There are several genera of Asteriidae 

 that do not occur in northern seas, while most of the northern genera 

 are entirely lacking. Thus there are no species of true Asterias, 

 Pisaster, Orthasterias, Evasterias, Urasterias, Allasterias. It is 

 doubtful if there is any true Leptasterias, though some antarctic 



1 The apparent thickness of the dermis depends much on the mode of pres- 

 ervation, which should be stated in descriptions. It is hardened and con- 

 tracted by strong alcohol, and still more when dried, especially after being in 

 alcohol. In alcohol of about 70 per cent it is more naturally preserved. In 

 very weak alcohol and in formalin it may swell up and become soft. Some 

 of the difficulties in the identification of such starfishes are thus due to the 

 mode of preservation. In more cases it is due to the negligence of the describer 

 in not cleaning and describing the skeletal plates and pedicellariae. 



