INTRODUCTION, X1X 
In 1888 occurred the specific reinstatement of Tvstacella scutulum, 
chiefly by the aid of Mr. C. Ashford’s exquisite dissections. Strictly 
speaking, however, it would be more correct to speak of it as the definite 
installation of both forms—Z7’. haliotidea and 7. scutulum—as distinct 
species and members of our fauna. 
With one notable exception, this closed the list of the definite replace- 
ments of valid species, although during the next few years various forms 
were from time to time described as new to this country or to science, 
which eventually proved to be pure synonyms or simple varieties of 
already-known species. 
An excellent piece of work by Dr. Scharff was his superb Monograph, 
“he Slugs of Ireland,” which evinced sound work and careful investi- 
gation, while numerous papers and books by Mr. W. E. Collinge, Mr. J. W. 
Williams, Mr. W. A. Gain, Mr. Lionel E. Adams, Prof. T. D. A. Cockerell, 
and others, testified to the keen interest aroused in the study by the 
stimulus first given in 1882. 
The last important re-discovery —Limaa tenellus—was made in 1904, 
when the Rev. R. Godfrey, who had previously collected the species in 
Switzerland, sent numerous examples, collected in Rothiemurchus Forest, 
to Mr. Roebuck, who was at once able to verify the species as the long-lost 
Limazx tenellus, probably hitherto overlooked by the nature of its habitat, 
and it was a great satisfaction to be able once more to vindicate the sound 
scientific ability of its original finder, the late Mr. Joshua Alder. 
In conclusion, though the probability of further discoveries of truly 
distinct species is not great, yet it 1s not impossible that closer research 
and careful anatomical investigation may ultimately reveal other forms as 
yet unsuspected or it may be confused with the more abundant and 
widely-distributed species. 
