MONOGRAPH OF BRITISH LAND AND FRESHWATER MOLLUSCA. 71 
Limax tenellus Miiller (em. Nilsson). 
1774 Limax tenellus Miiller, Verm. terr. et fluv., ii., p. 11, no. 210. 
1822 — ftenellus Nilsson, Hist. Moll. Svecize, p. 11 
1848 —_ serotinus Schrenk, Land u. Sussw. Livlands. 
1849 — cereus Held, Land Moll. Bayern, p. 15. 
1852. — fulvus Normand, Desc. Limac. Nouv., p. 7. 
1852. —_ sylvaticus Dum. & Mortill., Moll. Savoie, p. 10. 
1862 cinctus Heynemann, Mal. BL. ST 5) Tn 101. 
1868 Malacolimoas tenellus Malm, Skand. Limae., p. 66, pl. ii1., ff. 7-7f. 
1869 Arion tenellus Letourneux, Moll. Vendée, p. 7. 
1882 Agriolimax tenellus Less. & Poll., Monos. Tae Ital., p. 45, pl. 1., f. 7. 
ISTORY.— Limax tenellus (tenellus, very 
slender or delicate) was first discrimin- 
ated by Miiller, whose name is accepted 
by Nilsson, the obvious error in the mea- 
surement being disregarded. 
Heynemann, however, is of opinion 
that Miiller’s Limax tenellus is really 
an Arion, but ascribes to the tenellus of 
Nilsson the Lima succineus, L. flavus, 
and L. e/nctus, all of Miiller, the LZ. suc- 
cineus and L. flavus bemg referred to 
the unicolorous, and L. e7netus to the 
banded form. 
He also regards the Limaa collinus 
Normand and the Limaa aureus Gmelin 
as probably also referable to this species. 
he late Dr. A. W. Mahn, the eminent 
Swedish naturalist, with whom the pre- 
sent species has been associated, was so 
greatly impressed with its characters 
that he instituted a new genus, Mala- 
colimax, for its reception, based upon 
the soft body, the tricuspid median-tooth, and the di-ectoconic marginals. 
Lessona & Pollonera, while adopting Malm’s name of Malacolimas as of 
sub-generic value, place it under A griolimax, but, as shown by Simroth, it 
is probably most correctly associated with the typical Limaces, of which it 
is an ancient form, though he places it with L. cephalonicus and L. subsaa- 
anus In a separate section, which he stvles Microheynemannia to distinguish 
it from the Macroheynemannia to which Limaxr maximus and the larger 
species are relegated. 
Diagnosis.—Limax tenc/lus differs from the species to which it is struc- 
turally most closely allied by its much smaller size, yellowish colour and 
black or blackish tentacles, its semi-transparent shell, ‘and yellow mucus. 
INTERNALLY, the reproductive organs are simple, the penis-sheath is short 
and swollen, and its retractor fixed near to and in front of the heart; the 
alimentary canal is almost a counterpart of that of juvenile Lamar maximus, 
except that it presents indications of a coecum or rectatheca.' 
Original Description. —210. LIMAX TENELLUS. LIMAX virescens, capite tenta- 
eulisque nigris; long. 10 unc. Totus albidus Clypeus in luteum, abdomen in vire- 
scentem colorem aliquantum vergit ; ille margine postico, hoc apice supra nigricat. 
In Fossulis Nemorum foliis aridis repletis ; primo vere. Miill.,Verm. Hist. 11, p. 11. 
1 Monog. i., p. 284, f. 566. 
