C. CROSSLAND—NARRATIVE OF THE EXPEDITION. 4 
fold the tentacles simultaneously over the mouth and straighten them again, 
is one of the strange things to be seen by the use of a water-telescope. The 
phenomenon is, I believe, unique among fixed Ceelenterates. 
Tubipora is comparatively rare on this coast, though I believe that in other 
parts of the Red Sea it is as abundant as in the shoals of Zanzibar Channel. 
The Planarians* are a group which is only beginning to be known and 
of which large collections must be slowly accumulated betore true com- 
parisons of faunas can be made, but I believe a considerable resemblance 
between the two regions will be shown by Mr. Laidlaw’s papers. 
To the Opisthobranchs | the same remark applies, and in addition the 
migratory habits of many species make it impossible to obtain a fair 
collection in less than a year’s time. The difference in the conditions 
under which collection was carried on will account for differences in the 
lists of species quite independently of the real facts of distribution. For 
instance, the very large and conspicuous Hewabranchus was quite common 
about Zanzibar, whereas here I have seen but one specimen. On the other hand, 
I believe I collected only one specimen, and that a small one, of Chromodoris 
elizabethina on the equatorial coasts; here I have collected many and have 
seen, | confess, more than I have captured. I have never yet seen here 
the great swarms of Aplysiidee which I met with on the shores of Zanzibar 
and the Cape Verde Islands. 
The Echinodermata are in both localities characterized by the abundance 
and beauty of the Comatulide and the large size of the Holothurians. The 
Jatter are not fished as “Trepang” in the Red Sea, the several valuable 
species known as “ Teat fish ” being rare or absent. 
The brilliant Pentaceros Lincki is common here as in Hast Africa and 
Ceylon; as are the species of Linckia, of which all stages of its peculiar 
vegetative mode of reproduction are to be met with frequently. 
The single littoral Oligochzete is a new species, and has been described 
under the name Pontodrilus crosslandi by Mr. Beddard ft. | 
Polycheta.—The ease with which a fair number of species of this group 
may be collected, together with the diversity of their habits and habitats and 
the fact that most of them are practically fixed organisms, make the group a 
specially useful help in studying problems of distribution. Of the few 
Equatorial species I have so far had opportunity of identifying §, all the 
* F. F. Laidlaw, P.Z.S. 1903, pp. 99-118, & 1906, ii. pp. 705-719 (two papers on the East 
African Collections). 
+ Sir E. C. Eliot, P. Z. S. 1902, ii. pp. 62-72; 1908, i. pp. 250-257, ii. pp. 854-385 ; 1904, 
i. pp. 886-406, ii. pp. 83-103, 268-298, and onwards; aiso ‘Journal of Conchology,’ xi. 
(1905) pp. 237-256, (1906) pp. 298-315, 366-367. 
} P.Z.S. 1905, ii. [1906] pp. 558-561. 
§ C. Crossland, “Fauna of Zanzibar,” &c., P. Z.S. 1903, i. p. 169, and onwards to 1904, 
i. pp. 287-330. 
