334 Miller—The Anatomy of the Heart of Cambarus. 
LIGAMENTS. 
As was stated early in the paper, the heart does not lie free 
in the pericardial chamber, but is attached to its walls by means 
of the arteries and certain band-like structures, called liga¬ 
ments. The arteries have been described, and it remains for 
me to take up the ligamentous attachments. 
Huxley describes six ligaments, three on each side, as being 
present in the heart of Astacus; of these three, two are attached 
to the anterior dorsal angle of the heart and one to the pos¬ 
terior. Dogiel 4 has recently described the ligaments of the 
heart of the same species as being made up of fine fibres which 
are attached to the entire surface of the heart. These fibres 
pass in different directions, interlace and unite to form broad 
bands, which are attached to the walls of the pericardial cham¬ 
ber. 
As the result of numerous dissections, I find in Cambarus an 
entirely different arrangement, which may, perhaps, be said to 
be a combination of the views of Huxley and Dogiel. 
Attached to each angle of the dorsal surface of the heart is a 
broad ligament; the two attached to the anterior angles have a 
forward, upward and outward direction, while those attached to 
the posterior angles pass backward, upward and outward to be 
attached to the walls of the pericardial chamber. 
Besides these, I find a broad band attached all along the 
ventral border of the lateral surface, which extends directly out¬ 
ward to be attached to the wall of the pericardial chamber. The 
place of the attachment of this lateral ligament to the heart is 
indicated in Figs. 5 and 6, PI. VI. 
ACTION OF THE HEART. 
Each pulsation of the heart consists of a stage of strong con¬ 
traction, termed its systole, followed by a stage of dilatation 
or diastole. During its systole the heart becomes shortened 
and much narrower; this is due to the contraction of the longi¬ 
tudinal and circular muscle fibres already mentioned. 
4 Beitrag z. verglich. Anat. u. Phys., d. Herzens. Arch. f. mik. Anat., 
1894. 
