10 
THE VOYAGE OF H.M.S. CHALLENGER. 
Synapta glabra, Semper, 1868 (PL I. fig. 6). 
Habitat . — Zebu Eeefs ; several mostly rather incomplete specimens. 
I hesitated long whether to refer the animals in question to Synajpta glabra, 
Semper, or to Synapta grisea, Semper, or Synapta serpentina, Muller, forms which are 
very nearly related to it. According to Semper, however, the fact that the branches of 
the tentacles are webbed together by a thin membrane characterises Synapta glabra and 
distinguishes it from the remaining forms. Some of the specimens brought home from 
Zebu Eeefs also seem to be in possession of such a web between the branches or digits, 
which are rather short, while in other forms this web is almost inconspicuous. Mostly, 
the branches of the tentacles are highly contracted, whence it is difficult to discern their 
arrangement, a difficulty greater inasmuch as the animals themselves have undergone 
some changes by reason of their long immersion in spirits. .The calcareous ring is more 
nearly allied to that of Synapta glabra than to those of the other species. The stock 
or handle of the anchor (PI. I. fig. 6, a) is provided with six to eight small processes 
wEich are rough with minute spines, and that part of the anchor where the arms 
or flukes join each other carries as many as eight or more small teeth. 
Colour in alcohol, dark brownish on the upper surface and lighter on the under. 
Length of the largest specimen about 500 mm. 
Another individual, also obtained at the same Station, possibly forms another species, 
but unfortunately the calcareous matters have been dissolved by the impure alcohol, and 
the crown of tentacles is destroyed, so as to make closer investigations impossible. 
Synap)ta lappa, Muller, 1850 (PI. I. fig. 7). 
Habitat. — Gomera, off Tenerife, February 10, 1873; depth, 70 fathoms; several 
fragments. 
The highly macerated and fragmentary condition of the individuals I have had at my 
disposal prevents minute examination. To judge from what I have observed, they 
must belong to this species of Muller. The Polian vesicles, the single madreporic canal, 
the shape of the calcareous ring and of the deposits in the body-wall, &c., agree most 
strikingly with the description of Muller. The tentacles, however, fifteen in one 
individual and sixteen in another, do not seem to be of quite equal size. Besides, the 
anchors have, as a rule, anteriorly where the flukes join each other, as many as eight 
small teeth. The numerous miliary granules resemble those in Synapta grisea. Semper, 
and Synapta glabra. Semper. 
Synapta picta, n. sp. (PI. I. figs. 9, 10). 
Tentacles twelve, each with about twenty-five digits ; one ventral tentacle con- 
siderably smaller than the others. Calcareous deposits closely resembling those in 
