388 
THE VOYAGE OF H.M.S. OHALLENGER. 
Family Halelminthida:. 
Few examples of this group seem to have been noticed by explorers. None are 
indicated by Grube in the “ Gazelle,” but he describes one in the collection made by the 
Novara Expedition, and two in that from the Philippines. Schmarda and Kinberg give 
no addition to our knowledge of the family. 
The genus Notomastus ranges from the littoral region, where it is abundant, to con- 
siderable depths, e.g., 1340 fathoms, or, as mentioned by Ehlers in the “Porcupine” 
collection, 1443 fathoms. Caigitella reaches about half that depth. They are partial to 
muddy ground, though on the east coast of Scotland they are frequent in sand. 
They are common in the seas of Greenland, occur at various points between it and 
Madeira, and probably extend much farther south. 
Eunotomastus, n. gen. 
Eunotomastus gruhei, n. sp. (PI. XXIVa. fig. 16). 
Habitat — Dredged at Station 33 (off Bermuda), April 4, 1873 ; lat. 32° 21' N., long. 
64° 35' W.; depth, 435 fathoms ; surface temperature, 68°’0 ; sea-bottom, coral mud. 
The specimen is fragmentary and much injured, apparently having been partially 
dried, so that the description is imperfect. It measures about 30 mm. in length and 
1 '8 mm. in breadth. 
It seems to have a short conical snout devoid of eyes. The general appearance of the 
anterior region agrees with Notomastus, though the segments are longer, and the central 
furrow less marked. A few of the anterior bristle-tufts are absent, but about sixteen 
pairs appear to have been present. The bristles agree in structure with those of the 
common Notomastus, though they are somewhat shorter. 
The second region of the body is not differentiated in the same manner as in the 
ordinary form, the anterior gradually merging into the succeeding. The dorsal bristles 
are continued (in four segments) after the commencement of the hooks. The latter 
(PI. XXIVa. fig. 16) show much more distinct teeth on the crown, and their shape also 
diverges. An evident enlargement occurs just within their insertion. 
The segments of the second region of the body differ from those of the common British 
form and others in presenting none of the transverse ridges dorsally, only slight pro- 
minences for the rows of hooks. The ventral ridges are also simple transverse elevations. 
It is unknown whether this or any of the previous forms possesses branchiae 2 :)osteriorly, 
since no trace of that region remains. 
Fragments of sponge-spicules, minute Foraminifera and Eadiolarians, with coarse 
sand-particles, are present in the alimentary canal. 
