1098 REPORT—1885. 
and in acuta the outline is that of a long isosceles triangle, with the sides about 
two to three times the length of the base. 
The chief works on the subject are as follows:—Miiller, ‘Die Wiirmen,’ &c., 
1775 (digitata) ; Roésel, ‘ Insecten-Belustigung,’ 1761 (palpigera) ; D’Udekem, 
‘Bull. Ac. Roy. Brux.’ 1855 (obtusa and digitata) ; Semper, ‘ Arbeit. Zool. Inst. 
Wurzb.’ 1877 ( philippinensis and Rodriguez-palpigera); Leidy, ‘ American Natu- 
ralist,’ 1880 (limosa); Vejdovsky, ‘System und Morphologie der Oligochaeten,’ 
1884 (the whole subject); Perrier, ‘ Arch. de Zool. Experiment, 1872 (obtusa ?). 
I have not found it possible to identify Miiller’s species as yet. His figures have 
been copied by all who have given figures of D. digitata, and no trustworthy one 
exists. Recent writers have only recorded the fact of having found it, or given 
a verbal description. Perrier’s D. obtusa is a new species, and I have named it 
D. Perriert for convenience of reference. D. latissima is described for the first 
time. D. acuta is also new. It is probably one of the ¢wo species figured as 
digitata by Miller. D. palpigera of Grebincky was first figured by Rosel (loc. cit.), 
and redescribed as D. Rodriguezii by Semper. The latter also described D. philip- 
pinensis, but did not figure it, so that the identification of it is doubtful; a remark 
which also applies to imosa, of which only a small outline figure is extant. 
Further investigation may prove that the species which I have described and 
figured under those names are new British species, in which case all the species 
included in my diagnosis, except palpigera, are British, and to be found near 
London. Their number will probably be added to as time goes on. 
The following is a complete list of known species :— 
1. Dero obtusa. The processes short, stunted, flat, four in number. 
2. Dero Perriert. Four cylindrical processes, well developed. 
3. Dero latissima. Four long flattened cylindrical processes; the branchial 
area expanded into two large wings. 
4, Dero palpigera. ‘The branchial area terminating in two long, non-ciliated 
tentacles. The branchial processes four long cylindrical, and two shorter supple- 
mentary ones. 
5. Dero limosa. Four foliate processes, of considerable length; two short 
supplementary cylindrical ones springing from the angles of dorsal lip. 
6. Dero philippinensis. Characters as imosa, but the supplementary processes 
springing from a common root. 
7. Dero digitata. The last segment terminating in two very long processes ; 
four branchial processes. 
8. Dero acuta. Characters as limosa, but the four branchial processes long and. 
triangular, and the area convex in full expansion, with everted edges. 
The foregoing descriptions apply to the asexual form; I have only seen the 
sexual form of the second and third species named. 
11. On some little known Fresh-water Annelids. By HE. C. Bousriexp. 
12. On the Coloration of the Anterior Segments in the Malanide. 
By Professor ALLEN Harker, F'.L.S. 
13. Systématique du genre Polygordius. By Juumen Frarponr. 
14. On some of our Migratory Birds, as first seen in Aberdeenshire. 
By James TAyior. 
Some notes on the first arrival of our summer visitants among birds, so as to 
give some idea of spring migratory movements. The migration of birds and its 
causes have occupied the thoughts of eminent ornithologists, It is not our purpose 
to understand the principle of instinctive movements, but sufficient to say that 
