DB. A. GUNTHER’S DESCRIPTION OF CERATODUS. 
567 
Fig. 7. A longitudinal section of a dermo-neural cartilage, magn. 216. 
Fig. 8. Cartilage-cells from a joint of a fore paddle, magn. 216. 
PLATE XXXVII. 
Heart and Gills. All figures of the natural size. 
Fig. 1. Front view of heart of Ceratodus miolepis. 
Fig. 2. The ventricle opened. 
Fig. 3. The ventricle and atrium opened. 
Fig. 4. The ventricle and transverse portion of the conus arteriosus opened. 
Fig. 5. The right side of the heart opened, to show the spiral valve within the conus. 
Fig. 6. Ganoid valves in a normal state of development. 
Fig. 7. Ganoid valves partly rudimentary. 
a. Atrium. 
b. Conus arteriosus. 
c. Large valve between atrium and ventricle. 
d. Papillary valve within the conus, with its muscle ( d '). 
e. Transverse series of large ganoid valves. 
f. Eaised stripes f? rudimentary valves). 
g. Transverse series of small ganoid valves. 
g'. The same reduced to a pair of small papillary prominences. 
7i, i. Anterior arcus aortae. 
7c, l. Posterior arcus aortse. 
m. Papillary muscle, with its cartilage (to'). 
v. Ventricle. 
Fig. 8. Gills of the right side. The scapular arch has been removed, and only a small 
portion of the left coracoid ( co ) is preserved ; the ceratohyal (ch) is pulled 
forwards, beyond the mandibulary joint of the suspensory pedicle (sp). The 
glossohyal ( gl ) and suboperculum (so) are also preserved in this preparation. 
h , i. Anterior arcus aortse. 
7c, l. Posterior arcus aortse. 
u. Attachment of the first gill to the roof of the gill-cavity. 
u'. Attachment of the fourth gill to the suprascapula. 
x. Pseudobranchia. 
V. One series, and x" the other series of gill-rakers belonging to the 
pseudobranchia. 
Fig. 9. Anterior parts of the aorta. The branchial arches of the left side are drawn 
outwards, to show the arrangement of the gill-rakers. The ceratohyal (ch) is 
drawn forwards. Basal bone=Z»«. 
h, i. Anterior arcus aortse. 
7c, l. Posterior arcus aortse. 
4 i 
MDCCCLXXI. 
