AGRIOLIMAX LEVIS. 123 
tory organ, which differs from that of A. agrestis in being shorter and more faintly 
erooved : the PENIS-RETRACTOR is short, and arises from the lung-floor, considerably 
in front of the heart and the kidney in the European form, but is usually absent in 
L. campestris and its allies. 
The ALIMENTARY CANAL somewhat resembles that of A. agrestis, but the INGES- 
TIVE TRACT is still shorter, and the rectum is quite free of any ececal process ; the 
SALIVARY GLANDS are slender and rather deeply lobed ; the LIVER is usually of a 
pretty moss-green colour; the right lobe forms the hinder end of the visceral mass, 
the left lobe is also quite forward and divided into a number of slender points or tips. 
The RETRACTOR arises from the right side of the median line, behind the kidney, 
from a bifid or trifid root, which after a longish course unites into a slender band 
which fureates about mid-way; the BUCCAL retractors are quite slender and linear, 
while the TENTACULAR branches, though originating from the common stem as a 
slender band, soon become very bully. 
The MANDIBLE or jaw is of the usual ecrescentic 
form, with less produced limbs and much more > 
prominent and convexly rounded rostrum or beak -_ 
than in A. agrestis; the colour is brown, darkest 
along the upper margin and towards the extremi- Fic. 135.—Mandible or jaw of 
ties of the lateral limbs; the eutting edge is also A. éawis, x 20. 
finely serrate along its whole extent. (Armley, Leeds). 
The LINGUAL MEMBRANE 1s elongate, about three mill. long, and one mill. broad, 
the transverse rows being arranged in arcuate form, bending distinctly backw: rds 
towards the margins ; median row of teeth with well dev eloped mesocone and ecto- 
26 
20 2 
4 
Q “ | 
Fic. 136.—Representative denticles from a transverse row of the lingual teeth of 4. Zeus, x 240. 
The animal collected at Horsforth, Leeds, and the palate prepared by Mr. J. W. Neville. 
cones ; laterals also tricuspid, the first and twelfth with endocone quite obsolete or 
indistinct; marginals aculeate or with an ectocone more or less distinctly visible. 
The dental formula of a HOON specimen shows 
to t+h5t+54+35418 x 115 = 6,555. 
Reproduction and Development. — The reproductive organs of 
A. levis, and to some extent those of the Limacidw generally, have been 
found by Dr. Babor to undergo a remarkable cycle of development, or 
series of metamorphoses, during which the individuals of this species, which 
are admittedly proterogynous, tindergo a series of changes from their primi- 
tively unisexual and purely female ‘condition to the hermaphrodite state, 
and afterwards become purely male by the atrophy of the female organs. 
These wonderful mutations are demonstrated by the fact that most of 
the individuals found in spring are unisexual with a purely female organi- 
zation, possessing gonads yielding ova only ; later the examples show a 
budding of the male organs, so ‘that in summer and early autumn the 
animals have become hermaphrodite, and present well developed organs of 
both sexes. ‘The evolutionary process, however, does not cease with the 
full acquirement of the hermaphrodite state, as Dr. Babor has found that 
after a certain interval the female organs may atrophy and dwindle away, 
and the animal again become unisexual, but purely male, with gonads 
secreting spermatozoa only. 
Even when the cycle is thus fully completed, it is not by any means 
certain that in some species the sequence of transformations may not be 
continued, and the rotation of sexes again take place. 
