Ill ZOOLOGY. 



feus of the sand-stars, the hipinnaria (Fig. 75) of certain 

 star-fishes, and the auricularia of the Holothurians. 



Fig. 76 shows the star-fish developing on the aboral end 

 •of the brachiolaria, whose body it is now beginning to ab- 

 sorb. The brachiolaria soon shrinks, falls to the bottom, 

 and attaches itself by its short arms. The star-fish com- 

 pletely absorbs the soft body of the larra, and is conical, 

 disk-shaped, with a crenulated edge. In this stage it re- 

 miins probably two or three years before the arms lengthen 

 ^nd the adult form is assumed. 



In Lcj)fijchaster kergtoelenensis Smith, of the South Paci- 

 :fic, a form allied to Luidia or Archaster, the yonng develop 

 -directly in a sort of marsupium, according to TVyville- 

 Thompson. Pter aster militaris was found by Bars to be 

 Tiviparous. 



In Brisinga the arms number from nine to twenty, are 

 long, cylindrical, and, like the body, bear long spines. The 

 •species are abyssal. B. ejidecacnemos Asbjoinsen lives on 

 the Norwegian coast, at a depth of about 200 fathoms, and 

 Tvas dredged in abundance by the Challenger Expedition in 

 1350 fathoms, at a station due south of St. (xeorge's Banks, 

 -associated with other species of star-fish {Zoroaster and As- 

 iropecten), and again in eighty fathoms on La Have Bank, 

 -off Xova Scotia. A common form living in mnd in usually 

 from ten to thirty fathoms is Ctenodiscus crispatus Eetzius, 

 in which the body is almost pentagonal, the arms being very 

 short and broad. Archaster is a genus of star-fishes occurring 

 at great depths, A. vexilUfer TVyville-Thompson (Fig. 77), 

 -occurring off the Shetland Islands, in from 300 to 500 fath- 

 oms. Luidia is called the brittle star-fish, as when bi'ought 

 up from the bottom and taken out of the water it breaks up 

 into f iiigments. It has five long arms. L. clatlirata is com- 

 mon ou the sandy shores of the Carolinas, and ranges from 

 Xew Jersey to the West Indies. Astropezten ariicidatus 

 (Say) has the same range. Astrogonium phrygianum Parel 

 is a large pentagonal, bright-red star-fish, living in twenty 

 to fifty fathoms on rocky bottoms in the Gulf of ]\Iaine 

 und northward ; while Pteraster militaris iliiller is an 

 arctic species which ranges south to Cape Cod. It is sub- 



