1064 
SCANDINAVIAN FISHES. 
legists have succeeded in explaining the equivalent 
parts of the preceding fishes, where these are more 
and more simplified by reduction, as well as the cor- 
responding structure of the higher vertebrates. In some 
Elasmobranchs (the Rays, fig. 293) the shoulder-girdle 
forms a closed, flattened ring around the anterior end 
of the abdominal cavity and the spinal column behind 
the last branchial arch, being suspended over the con- 
tinent neural spines of the anterior part of the spinal 
column. The upper part of this ring consists of the 
two simple suprascapular disks, one on each side of 
articular condyles (for the pectoral fin), set in an hori- 
zontal row. The. scapular part lies above the coracoid; 
but both of them form a continuous cartilaginous disk, 
and are also of a piece with the lower median port of 
the ring. The last-mentioned part has been interpreted 
by Parker as an equivalent of the epieoracoid bone of 
the higher vertebrates, where this bone is distinct 
even in the lowest mammals. In most of the Elasmo- 
branchs (the Sharks and Chimaeras, fig. 294), however, 
the suprascapular cartilages ( ssc ) are parted from each 
other and suspended from the membranous investment 
A 
0 
B 
Fig. 293. Skeleton and shoulder-girdle of the Rays. 
A: Skeleton of a Skate ( Raja nidrosiensis ), cf 1 , seen from the dorsal. side. 1 / 10 . Trondhjem Fjord, March 17, 1891. Conservator Storm. 
B: Shoulder-girdle of a Thornback ( Raja clavata), seen from the ventral side. 1 / 2 . After Parker, v, part of the spinal* column; gl, the 
first of the three lateral processes furnished with articular surfaces for the pectoral fin; cr, coracoid part; e. cr, ventral side of the shoulder- 
girdle (epieoracoid part). 
the spinal column. The sides thereof are formed by 
the much more expanded scapular and coracoid parts, 
which are pierced with large foramina (for the passage 
of nerves and blood-vessels) and furnished with three 
(. aponeurosis ) of the dorsal muscles only by a prolonga- 
tion of their own investing membrane {perichondrium), 
the whole girdle too being more simple and not unlike 
the pelvic girdle. The cartilage of the latter (figs. 293, 
