38 MARINE BIOLOGY OF THE SUDANESE RED SEA. 
the characteristic markings are very indistinct ; the papillz in the centres of 
the lighter areas are small and can only be made out by the aid of a lens. 
The second and third arms on the left side and the third on the right have 
been lost and their replacement has commenced. The rudiments of the new 
arms grow out just below the skin on the outer 028 as mentioned in the 
case of P. horsti, Hoyle, 1907, p. 452. 
Three specimens (1083-1085), found together, must I think be melanic 
examples of this species. In strong sunlight I can see indications of the 
circular lighter-coloured areas, expecially in the larger example, which 
measures 25 mm. from the posterior end of the mantle to the centre of the 
eyes. In the smallest, the corresponding measurement of which is 18 mm., 
they are barely distinguishable ; but the three resemble each other so closely 
that they undoubtedly belong to one species. These specimens were collected 
half a mile beyond the Bachet Hotel, where a tidal stream flows from the flats 
into the canal. 
Potypus HorstI (Joubin). 
Octopus horsti, Joubin, 1898, p. 23. 
Polypus horsti, Hoyle, 1907, p. 451. 
Localities —Suakim Harbour, one young specimen, ? [1091], one specimen, 
9 [1337]; purchased from a fisherman; one specimen, ¢ [1081]. 
Previous records.—Jeddah, Red Sea (Joubin) ; Zanzibar (Hoyle). 
In specimen 1337 the ocellar spots are very indistinct, especially that on 
the right side, showing that this character might be easily overlooked in 
certain conditions of the chromatophores. The length of the mantle is 7 mm.; 
the tip of the hectocotylised arm measures 4 mm. in length, and there are 
about a dozen delicate transverse ridges in the hollow. 
No. 1081 is a very puzzling specimen, and I was at first disposed to identify 
it as P. horridus. The zebra-like markings on the arms are hardly percep- 
tible, but the ocellar spot is very well marked indeed. The surface is very 
rugose ; above and behind each eye is a large wart with three or four wartlets 
upon it, and a small wart behind it. Above and before each eye is a small 
wart, whilst another still further forwards in the middle line forms a triangle 
with these two. There are four warts in the form of a small lozenge on the 
back and several others scattered irregularly about. The papilla at the 
posterior end of the mantle is pushed out of the centre and is made out only 
with difficulty owing to the stretching of the skin in that region. On the 
whole I regard it as an aberrant example of P. horsti. 
No. 1091 has a smooth surface and the ocellar spot, but the characteristic 
transverse barring of the arms is for the most part indistinct ; there are, 
however, traces of it here and there, and as the specimen is young these 
might very probably become better marked with further development of the 
individual. 
