PIXELL—POLYCHATA OF THE INDIAN OCEAN 79 
4. Uncini with about nine teeth, the anterior one larger and hollowed out underneath 
like a gouge (cf. Spirobranchus). 5. Uncinigerous tori of right and left side almost 
meeting on the ventral side of thorax, leaving only a narrow straight depression along the 
median line (Ehlers, 15, p. 297). 
9. Pomatostegus stellatus (Abildgaard) (1) 1789. 
Terebella stellata, Abildgaard (1) 1789. 
Pomatostegus stellatus, Mérch (37) 1863; Benedict (8) 1886; Ehlers (15) 1887; 
Gravier (21) 1908. 
The distinguishing characteristics of the several species of this genus that have been 
described do not seem to be at all clear. Bush (8, p. 499) states that P. stellatus has 
a smaller operculum and more elongated body than P. brachysoma, Schmarda, of which 
she gives a long description, mentioning 45 mm. as the length (but giving no width) of 
her one specimen. As a matter of fact, the one specimen of P. stellatus described in 
detail by Ehlers (15) is said to have a length of 35 mm. only, and to be composed of 140 
segments. P. macrosoma, Schmarda (48), has been said to differ from both of these in 
having (1) a divided ventral lobe to its collar and (2) a greater number of turns to the 
branchial spirals; however, the latter is said by Ehlers to be an unsatisfactory specific 
characteristic as is also frequently the special form of collar or thoracic membrane. 
Therefore P. macrosoma is probably identical with P. stellatus and possibly P. brachysoma 
also. 
Locality. Five specimens from “ the side of a coral block,” Suakin, Red Sea. 
These specimens vary in total length from 21°5—52 mm. and have 70—96 abdominal 
segments. They agree as to colour with the description given by Gravier, but I have 
only been able to find very few bladed sickles (setze of Apomatus) among the thoracic 
setae, the majority being rather short, stiff, simple and bladed forms. The abdominal 
setae have the rounded teeth described by this author, but have nearly lost their sickle- 
hike curve, this is, no doubt, due to their lengthened immersion in preservatives (ef. 
Saint-Joseph, 44, p. 334). The tubes are thick and irregular, overgrown with Polyzoa, 
Spirorbis tubes, &c. The cavity is, however, smooth and cylindrical, measuring 83—4 mm. 
in diameter. There is nothing else that need be added to Ehlers’ excellent description 
(15, pp. 296—300) of one specimen without a tube from Hast Key. 
Genus SPIROBRANCHUS, Blainville (6) 1817. 
Generic characteristics: 1. Operculum with a calcareous plate generally bearing 
a group of branched spines. Pedicle with broad lateral wings. 2. Collar sete as in 
Pomatostegus. 3. Abdominal sete trumpet-shaped, the edges compressed and toothed 
and produced at one place into a long fine point. 4. Uncini the same shape as in 
Pomatostegus, but with rather more numerous teeth (9—25). 5. Uncinigerous tori 
of the two sides widely separated ventrally in front and gradually approaching one 
another towards the end of the thorax, thus leaving a triangular depression. 
