156 JOURNAL OF CONCHOLOGY, VOL. lO, NO. 5, JANUARY, I902. 



ARIONID.-E. 

 Arion ater, A. hortensis, 



A. siibfuscus, A. circuniscnptus, 



A. minimus, Geomalacus maculosus, 



G. anguiformis. 



PHILOMYCID/E. 



' Philoniycus caroliniensis, \ Pallifera dorsalis. 



There has been a tendency to regard thread-making as the exclu- 

 sive property of a particular spinning-slug ; but Liinax filans is a myth. 

 The faculty, as we have seen, is not confined to any particular family ; 

 and the three families just named, not immediately allied, are more 

 nearly related to certain snails than to each other. It was long ago 

 suggested that spinning is common to all slugs (4), and definite state- 

 ments that this is the case have been made ; but everything depends 

 on the nature of the slime, and this is known to differ from 

 species to species. It is possible, however, that the faculty may be 

 universal. Binney (20) saw it practised by every species of slug known 

 to him in the Atlantic States of North America ; and the writer's ob- 

 servations extend to all the species which he has seen in these islands 

 (except L. cinereo-niger and L. flaviis), namely, to L. viaxiinns, L. 

 arboruni, Amalia soiverbyi, A. gagates, Agriolimax agrestis, A. Icevis, 

 Arion ater, A. subfitscus, A. niiniiinis, A. hortensis, A. circu/nscriptus, 

 and Geomalacus maculosus. 



It has been stated that it is chiefly when young that slugs spin ; but 

 the faculty is related more to size and weight than to age, small species 

 spinning as well, or nearly as well, when adult as when young. Very 

 large slugs, which spin well when young, are generally too heavy to 

 do so when full-grown ; they sometimes allow themselves to glide from 

 an object as if about to spin ; but, instead of being retained by a 

 thread, they fall. Tolerably large individuals, however, can suspend 

 themselves ; this is the case, for instance, with adults of Amalia 

 sowerbyi, bulky slugs 2-2|- inches long, furnished with unusually tough 

 slime. Great grey slugs {Limax maximus) suspend themselves in pairs 

 at breeding time, but the cord by which they hang differs from the 

 ordinary threads of which we are now speaking. Mr. Standen assures 

 the writer, however, that he once saw an adult of this slug suspended 

 singly upon an ordinary thread, and that he has several times seen full- 

 grown Z. arborum similarly situated. 



Statements of several authors imply that slugs are commonly seen 

 hanging from various objects. The writer, however, who has been 

 interested in these animals for a number of years, and has often col- 

 lected them in woods, etc., by lantern-light at night, has never 

 happened to find one suspended. The statements often refer to Z. 



