OCR Text |
Show 132 MR. CYRIL CROSSLAND ON THE [June 16, On aphis and the cirriform gills of Hyalincecia, or even the complete absence of gills {Peeronuphis), so that in some cases the only distinction available is that provided by the presence or absence of tentacular cirri. Genus DIOPATRA. DIOPATRA NEAPOLITANA Clap. (Plate X I V . fig. 1.) Since Grube's enumeration in 1877 * of eighteen species but few fresh descriptions have been published (Langerhans, D. madeir-ensis t; Ehlers, D. chilensis %, redescribecl). This fact, and the very local distribution of the species given, probably indicate the existence of a very considerable amount of synonymy, though Kinberg's seven species, assuming the correctness of his figures, are distinct. It is thus the more remarkable that the species should have so wide a distribution as from the Mediterranean to the East coasts of Africa and North America §. The species is so abundant at low spring-tides on any sandy or muddy shore in East Africa, that it is strange that it has not been before recorded from this locality. The material of the tubes varies with the habitat-on a sandy beach being built of shell-f r-agments or small stones, the edges always projecting horizontally, on muddy shores the grass-like leaves of Zostera or any suitable vegetable fragments being employed. Only the projecting and the upper two or three inches of the buried portions are thus strengthened, the remainder being soft and collapsable. Dark green and umber-brown coloured varieties of the animal occur, both colours being destroyed by a brief immersion in alcohol. The only specimen I obtained from below the level of lowest tides (from 10 fathoms in Wasin Harbour, the mainland coast) shows a third distinct variety ||. The living worm Avas red- (not umber-) brown anteriorly, the colour remaining distinct after immersion in strong spirit for more than a year. The gills were red, the colour of the blood not being hidden by green and brown pigments as in the preceding varieties. Structurally, I find this specimen to agree with the shore forms. The presence of similar pigmentation in preserved specimens obtained from Naples suggests that this colour variety occurs there also, and is probably the variety of colour which is described by Claparede as " ferrugineuse." It is possible, of course, that green, umber, and red-brown pigments may occur occasionally in the same individual, though I have not seen cases of this in East Africa. The lack of perfect completeness in Claparecle's account, and the obviously diagrammatic nature of at least two of his figures, made it impossible to decide whether I was examining a nearly related species or a variety only. A comparison of specimens obtained from Naples with m y own from Zanzibar has enabled me to * ' Mitth. fiber die Familie der Euniceen,' Naturw. Schles. Ges. 1877. t Z. Wiss. Zool. xxxiii. pp. 513-593. X ' Polych. des Magal. u. Chil. Strandes,' 1901. § Andrews, loc. cit. | Very numerous tubes were dredged from 3 fathoms in one spot in Chuaka Bay. |