726 HaroLD HEATH, 
fundamental resemblance between the two than has been generally 
recognized. Not only is the heart similarly located in both groups 
but in the relation of the aorta to the gonad and head cavity there 
is a similarity. The distribution of blood to the gonad in Limifossor 
could not be accurately determined but in Proneomenia hawaüensis 
the aorta sends off branches which penetrate between the halves 
of the gland and enter a sinus along its mid ventral line. From 
here they pass dorsally along the sides of the gonad and open into 
the visceral cavity very much as PLATE (1897) has shown to be 
the case with the chitons. Another very important feature is the 
septum bounding tlie head cavity behind and the relation of the 
aorta to it. The peculiar position of the anterior part of the pedal 
sinus has been explained on page 717. 
On the other hand it cannot be denied that the thinness of the 
mantle and the smallness of the foot are correlated with many 
peculiarities. The visceral artery is absent and all of the blood 
leaves the head cavity through one opening, that of the pedal sinus. 
Beyond the septum two lateral sinuses appear surrounding the pedal 
nerves while the lateral nerves are exposed in the visceral cavity. 
It is a significant fact however that these differences are concerned 
chiefly with the ventral half of the body or exactly that portion of 
the animal which, in the diminution of the foot, has been most 
modified. 
While many fundamental resemblances between the nervous 
systems of the solenogastres and chitons have been recognized by 
zoologists generally it is also well known that as hitherto described 
the correspondence is by no means complete. THrELE (1902) especially 
has called attention to the fact that the so called buccal systems 
have very few points in common. In a recent paper describing a 
subradular organ and its nerve supply in the solenogastres I have 
shown that the correspondence is remarkably close, more so in fact 
than I recognized at that time. 
Referring to the diagram A it will be seen that in the 
prosobranchs the labial ganglia, attached to the cerebral ganglia, 
by connectives are also united with the buccal system in which the 
commissure passes dorsal to the radula. In Lottia gigantea, which 
has been most carefully worked out in my laboratory by Mr. W. 
K. Fisner (1904), the buccal ganglia also give off nerves which 
very nearly form a collar about the pharynx and finally it is a 
a ee ier 
