Page:The Zoologist, 4th series, vol 1 (1897).djvu/333

Rh In 1838 Eversmann published an article in Russian on a night-shining worm (Lumbricus noctilucus, see Zapisk. Kazan. Universit., 1838, pp. 156–7), and in 1871 Breese, an English naturalist, delivered an address on the Earthworm before the West Kent Natural History Society, from a meagre abstract of which we learn that he had spent some years on the subject of annelid luminosity, having studied it historically from the year 1805, when Viviani wrote on the phosphorescence of the sea, down to the date of his own investigations. According to Breese the luminosity exists in the excreted glutinous material with which the outer skin of the animal is covered. It is much to be regretted that (so far as I can learn) the researches of this naturalist have never been given to the public in detail.

More than one creature has at different times borne the name of the phosphorescent worm. In 1837 Dugès, a French writer, described a species under this name (Lumbricus phosphoreus) with a girdle extending from the 13th to the 16th segments, and a somewhat flattened body behind. After the lapse of exactly half a century this curious creature was examined again, and named by Giard Photodrilus, or the luminous worm. It has eight setææ just as our common species have, but they are separate, and not in couples. There is no gizzard, nor does the lip dovetail into the segment behind. It is a small, transparent, rose-coloured worm, and decidedly phosphorescent.

A paper on this worm by Barrois appeared some time ago under the title "Sur la presence du Lumbricus (Photodrilus) phosphoreus, Dugès, à Groffliers (Pas-de-Calais)" in the 'Revue Biolog.,' iii. pp. 117–119. Beddard places it under the genus Pontodrilus, and gives the following brief summary of its characters and history:—

"—Length 50 mm.; diameter 2 mm.; number of segments 110. Setæ in eight rows. Clitellum xiii.–xvii. Hearts in x.–xii. Sperm-sacs in xi., xii. Spermathecæ in ix. with a diverticulum. Habitat—France.

"This species has been investigated by Giard, who, however, has not yet published an illustrated account of his researches. The main facts in its structure are given in the above definition. In addition to the points there mentioned there exist on segments xii., xiii., and xviii. sacs of modified setæ in addition to