196 ZOOLOGY. 
.teus of the sand-stars, the dipinnaria (Fig. 138) of certain 
star-fishes, and the auricularia of the Holothurians. 
Fig. 139 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 larva, and is conical, 
disk-shaped, with a crenulated edge. In this stage it re- 
mains probably two or three years before the arms lengthen 
and the adult form is assumed. 
In Leptychaster kerguelenensis Smith, of the South Paci- 
fic, a form allied to Luidia or Archaster, the young develop 
directly in a sort of marsupium, according to Wyville- 
Thompson. Pteraster militaris was found by Sars to be 
viviparous. 
In Brisinga the arms number from nine to twenty, are 
long, cylindrical, and, like the body, bear long spines. The 
species are abyssal. B. endecacnemos Asbjornsen lives on 
the Norwegian coast, at a depth of about 200 fathoms, and 
was dredged in abundance by the Challenger Expedition in 
1350 fathoms, at a station due south of St. George’s Banks, 
associated with other species of star-fish (Zoroaster and As- 
tropecten), and again in eighty fathoms on La Have Bank, 
off Nova Scotia. A common form living in mud in usually 
from ten to thirty fathoms is Ctenodiscus crispatus Retzius, 
in which the body is almost pentagonal, the arms being very 
short and broad. Archaster isa genus of star-fishes occurring 
at great depths, A. vewillifer Wyville-Thompson (Fig. 140), 
occurring off the Shetland Islands, in from 300 to 500 fath- 
oms. Luidia is called the brittle star-fish, as when brought 
up from the bottom and taken out of the water it breaks up 
into fragments. It has five long arms. L. clathrata is com- 
mon on the sandy shores of the Carolinas, and ranges from 
New Jersey to the West Indies. <Astropecten articulatus 
(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 Maine 
and northward; while Pteraster militaris Miller is an 
arctic species which ranges south to Cape Cod. It is sub- 
