THE SYNAPTAS OF THE NEW ENGLAND COAST. 
25 
nearly as much in diameter. Anchors and plates not essentially different from those of inlicerens. 
Calcareous rods in the sides of the tentacles and in the digits slightly curved and knobbed as in 
inhcerens; besides these, numerous branched, curved, and perforated rods and plates occur abundantly 
on the inner surface near the base of the tentacles. Calcareous particles in the longitudinal muscles 
C or doughnut-shaped, rarely branched. 
This species occurs between high and low water mark in gravelly banks or on rocky beaches, 
where there is considerable iron in the soil. Usually found near the surface and often underneath 
rocks. 
PHYSIOLOGICAL NOTES. 
Contrary to previous experience and to several writers on holothurians, I found 
during the summer of 1898 that Synapta inlicerens is very easy to keep in aquaria 
and roseola is about as hardy. On account of the greater abundance and larger size 
of the former, most of my observations were made on that species. When left in a 
vessel containing sea water only, the synaptas crawl about restlessly on the bottom, 
and unless fresh sea water is supplied they soon begin to constrict off parts of the 
body, beginning near the posterior end, and after a time nothing but small pieces will 
remain, and these soon die. If the supply of sea water is abundant and well aerated, 
this process may be delayed some hours, but it usually occurs in less than half a day. 
When, however, there is a sufficient amount of clean sand in the dish to allow the 
animals to burrow at will, they will live indefinitely if the supply of water is con- 
stantly renewed. By filling glass jars half full of sand, one is able not only to keep 
synaptas alive, but to study more or less of their underground habits. I agree 
entirely with Cu^not (’91) in believing that autotomy is not normal or defensive, but is 
due entirely to pathological conditions. I never saw a case of it in synaptas supplied 
with plenty of sand and an abundance of sea water. The fact that portions constricted 
off can not live is good reason for supposing the process is abnormal. An excess of 
magnesium sulphate in the water causes stupefaction and ultimate death, so that 
excellent specimens, either for laboratory purposes or for the cabinet, may be obtained 
by narcotizing with this salt and killing in strong alcohol or corrosive sublimate. 
Both species of synapta breed during the spring and early summer. The sexual 
glands are well developed by the last of April, and individuals with ripe ova may be 
found well into August. About the last of June or early in July seems the height of 
the breeding season at Woods Hole. Personally I have had no success with artificial 
fertilization of the eggs, but Dr. W. R. Coe, of Yale University, states that he has 
found no difficulty in fertilizing the eggs of 8. roseola, artificially, though he has made 
no attempt to carry their development beyond the segmentation stages. In that 
species the ripe genital glands show plainly through the body wall, and individuals 
in which the male elements fill the glands are easily distinguished from those in which 
the ova are mature. Further investigations into the breeding habits and embryology 
of our two synaptas are very much to be desired. 
Synaptas burrow into the sand head first and almost always go straight downward 
for some distance, but when once completely buried, they turn in any direction up or 
down or on the horizontal plane. They can and do turn in their burrows, but as a 
rule they make new tubes when they come to the surface. They are seldom still, and 
the old idea that they remained in the tube they have formed with their tentacles just 
above the surface is scarcely true. Sometimes they assume that position, but seldom 
remain so very long. They rarely leave their burrows and come out on the surface of 
the sand, and I doubt if they ever do so under normal conditions. 
Passage through the sand is chiefly accomplished by means of contractions and 
extensions of the body, but is materially assisted by the tentacles. With the latter, 
