30 
THE VOYAGE OF H.M.S. CHALLENGEE. 
Synapta henedeni, Ludwig, 1881 and 1882. 
Anchor-arms with some small, obtuse serrations. Anchor-plates slightly elongate, 
truncated at the articular end, thus in want of handle, with uneven margin and 
the numerous holes sparingly dentate in their margin. Miliary granules 
numerous, small, rod-like. Six Polian vesicles and a single dorsal madreporic 
canal. 
Sabitat . — Brazil (Ludwig). 
IV. Tentacles constantly eleven. 
Synapta tenera, Norman, 1864 (no description); MTntosh, 1875 ; Brady and Eobertson, 
1871. {?) Synapta inhcerens, Diiben and Koren, 1844 [partim). Synapta 
huskii, MTntosh, 1865—1866. 
Each of the eleven tentacles with three slender digits of almost equal length, or 
the terminal slightly larger ; behind these digits two or three transverse ridges 
may be found, by means of which the tentacles get the appearance of having- 
two or three pairs of short, obtuse processes behind the above-mentioned digits. 
These processes are not, however, true digits. Anchors with serrations on 
the arms. Anchor-plates rather characteristic, and differing from those of any 
other Holothurids ; they are very symmetrical, rounded, hexagonal, with a long 
narrow handle, which has regularly two small smooth perforations ; the plates 
themselves are pierced by seven dentate holes, of which that close to the handle 
is slightly smaller, transverse in position, and curvate. By means of those very 
symmetrically formed plates Synapta tmera approaches the group of Synaptse 
with numerous digits on the tentacles. No miliary granules (?). Body is most 
translucent, and of a pale flesh coloqr. Polian vesicle and madreporic canal 
single. Length about 35 mm. 
Habitat . — British Islands (Norman, Brady and Eobertson, MT-ntosh), Sognefjord in 
Norway (Danielssen and Koren). 
(Mus. Holm.) A very great number of specimens from the west coast of Sweden, 
where it is one of the most common animals, on a bottom of muddy clay. 
V. Tentacles ten, each with four digits and a small terminal tubercle. 
Synapta similis, Semper, 1868. 
Anchor-arms with serrations. Anchor-plates irregularly rounded with incomplete 
margin, and without handle but with numerous smooth holes. Miliary granules 
rod-like, cruciform. One to two Polian vesicles. A single madreporic canal. 
Habitat . — Bohol (Semper). 
