DK. A. GUNTHEB’S DESCEIPTION OF CEBATODUS. 
r.or. 
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remaining phalanges of this zone to coalesce into one piece (as, in nature, we find 
coalesced the carpals of Ceratodus , and many phalanges in Selachian fins), and when 
we repeat this same process with the following zones and outer series, we arrive at an 
arrangement identical with what we actually find in Ceratodus. 
The Pelvis and Pelvic Limb (Plate XXX. fig. 2, and Plate XXXVI. figs. 4-G). 
In the example figured the right ventral paddle is conspicuously narrower and gene- 
rally smaller than the left ; this is merely an individual peculiarity. The pelvis is essen- 
tially the same as in Lepidosiren and Protopterus (fig. 6) ; it is a single flattened sub- 
quadrangular cartilage with two paired processes and a single process. The posterior 
pair of processes are separated from each other by a deep semicircular notch, each ter- 
minating in a condyle to which the basal cartilage of the ventral paddle is joined. The 
anterior pair of processes are directed outwards and upwards, offering a point of attach- 
ment to the neighbouring lateral muscles of the trunk as well as to others stretching to 
the basal cartilage of the paddle. In our example the process on the side of the larger 
paddle is considerably broader and stronger than that of the opposite side. Thirdly, 
the single process arises from the middle of the front margin of the pelvic cartilage ; it 
is very long, cylindrical, tapering, and enclosed in a thick, shining, fibrous sheath (fig. 4, a), 
which is the continuation of the perichondrium of the pelvic cartilage. As is evident from 
this description, this process points forwards, towards the head, not backwards. So it is 
also in Lepidosiren and Protopterus. It lies imbedded between the abdominal muscles, 
in the median line of the abdomen in Protopterus , but bent somewhat towards the left 
side in our example of Ceratodus forsteri. If a vertical section is made through the 
pelvic cartilage (fig. 5), a capacious cavity ( b ) is found to exist in its interior ; but the 
state of preservation of our example did not allow of forming an opinion of the nature 
of its contents. 
The paddle is attached to the pelvis by means of a separate, rather short, subcylim 
drical cartilage which has a rounded process on its lower outer side ; it articulates with 
the pelvic condyle by a true joint, having a glenoid cavity in front. The endoskeleton 
of the paddle itself is almost identical with that of the fore paddle ; but the segments of 
the axial series of the right paddle (Plate XXXVI. fig. 4) are more liable to confluence ; 
the insertions of the branches are consequently more confused, and the phalanges are 
shorter, more feeble, and somewhat less in number. The skeleton of the left paddle 
(Plate XXX. fig. 2) is much more symmetrical and regular. 
The Organs of Circulation (Plate XXXVII.). 
The heart lies far forwards, its basal half being protected by the middle of the scapu- 
lary arch. It is enclosed in a pericardial sac with thick, tendinous walls ; the base of 
this sac is confluent with the diaphragm, which, like the proper tunic of the abdomen, 
is a strong glistening fibrous membrane. This is the only direct connexion between 
pericardium and diaphragm ; and a separate additional lamina extending from the dia- 
mdccclxxi. 4 E 
