1068 
SCANDINAVIAN FISHES. 
a coalescence of the anterior part of the spinal column 
similar to that just mentioned, and are without ribs. 
The ribs of the Elasmobranchs, however, differ essen- 
tially from those of the Teleosts in being more deeply 
embedded in the musculature (flesh), so that they are 
not immediately applied to the peritoneum, but in this 
respect more nearly answer to the scleral bones of the 
Teleosts and the ribs of the higher vertebrates. 
The skull forms a continuous capsule of cartilage, 
with no other limits between the separate parts than 
those indicated by the situation of the organs of sense 
and by the orifices of the cranial nerves. With their 
aid we can distinguish (/) an occipital region, around 
their postorbital ( ptob ) and preorbital ( prob ) processes, 
(4) an ethmoidal region, around the nasal capsules ( N ) 
with the internasal cartilage, and lastly (5) a rostral 
region, with the confluent tops of the primordial tra- 
becuhe (the basitrabecular tip, B) and the supporting 
cartilage (Jr) of the strongly developed rostral system 
of the lateral line. 
The occipital region is the shortest. In the most 
primitive forms the anterior end of the notochord ex- 
tends into the basioccipital part", and the foremost 
neurapophyses enter into the cerebral capsule. In the 
Sharks the articulation between the head and the first 
vertebra is commonly very little more developed than 
b 
Fig. 296. First dorsal fin with its skeletal parts and the subjacent part of the spinal column in a Cyclospondyle (Hasse), a Greenland 
Shark (Acanthorlnnus carckarias ), 230 cm. long, from the North Sea. J / 2 of the natural size. 
b, basal disk of the dorsal fin; ikt, rudimentary dorsal spine, hidden under the skin; fb, dorsal fin with its bunches of fibrils; r x and r 2 , first 
(proximal) and second (distal) rows of radialia; cr, lateral ridge of the basal disk, a projecting crest for the attachment of muscles; Ig , ver- 
tical ligament of the dorsal fin: le , elastic ligament of the spinal column; in, interneural cartilages (intercalaria neuralia ); na, neurapophyses; 
c, vertebrte, superficially constricted and each containing in the space between the constrictions a division of the spinal cord; dispondylic, 
each vertebra answering to two neurapophyses; h , heemal ridge, divided into haemapophyses (ha) and interhannal cartilages 
(ih, intercalaria hcemalia). 
the foramen magnum (figs. 298 and 299, fom), and 
limited in front by the nervus vagus foramen ( mg ), 
(2) a temporal or labyrinthine region, bounded in front 
by the true trigeminal foramen (figs. 294 and 300, tr), 
(3) a frontal (orbital) region, surrounding the orbits with 
in the Teleosts; but in the Rays (fig. 300) and the 
Chirmeras (fig. 294), as well as in some Sharks (fig. 
298, C and fig. 299), this articulation is accomplished 
by true condyles ( occ ), in the same manner as in the 
higher vertebrates. In the Chimseras, these condyles, 
See, for example, Chlamydoselache in Garman (Bull. Mus. Comp. Zool. Harv. Coll., vol. XII, No. 1), pi. VII, fig. B. 
