GADUS. 337 
posterior border (the preopercular, opercular, subopercular and inter- 
opercular), and joined to the quadrate by a small symplectic. Its lower 
half forms a chain of Ayo¢d bones which carry on their posterior surface 
seven branchtostegal rays. 
The four branchial arches consist of pharyngo-, ept-, cerato- and 
hypobranchials, united below by the daszbranchials. The pharyngo- 
branchials fuse to form the superior pharyngeal bones already noticed, 
and the Ceratobranchials of the fifth arch form the inferior pharyngeal 
bones. 
The vertebral column consists of a large number of amphicalous 
vertebre. The anterior are termed addomznal and the posterior are 
caudal, All the vertebree have complete neural arches and neural 
spines. Most of the abdominal have also transverse processes, which 
bear » pair of xzds and a pair of more dorsally placed so-called zxder- 
muscular bones. In the caudal vertebrae the transverse processes meet 
below and form a complete Aema/ arch. The median fins are sup- 
ported on dermal fin-rays, which rest on short pterygdophores and inter- 
spinous bones. 
APPENDICULAR.—The pectoral girdle is attached to the otic region of 
the skull by the supratemporal bone. There are three clavicular bones, 
the supraclavicle, clavicle and postclavicle. A small scapula and 
coracoid complete the girdle ; they bear on their posterior border four 
small brachial ossicles (or pterygiophores), which in their turn bear the 
numerous ectoral fin-rays. The pelvic girdle is absent, but there is a 
large basipterygium on each side which carries the pelvic fin-rays. 
The brain is small and differs from that of the skate, 
Nervous chiefly in the large optic Zobes and small cerebral hemt- 
System, spheres. On the other hand, the cerebellum is equally 
well developed. 
The gonads are simple, paired hollow sacs opening 
Reproductive.by short genital ducts to the exterior. They lie in the 
abdominal cavity. 
There is as great a contrast to the skate in the development as in the 
anatomy. The haddock lays several million eggs which are of small 
size, perfectly transparent and buoyant. Fertilisation is 
Development, external and the eggs are pelagic. There is a consider- 
able amount of yolk and segmentation is meroblastic. 
The young haddock is hatched as a transparent larva, with a large yolk- 
sac depending from its ventral surface. After a time the young fish 
absorbs its yolk and feeds on pelagic organisms ; still later it takes to a 
ground-feeding habit. : 
The haddock is a type of the order 7¢/costom# or bony-fishes, which is 
usually contained in the class Pisces, with the lasmobranchit and 
some smaller orders. It is, however, evident that the two types are 
widely divergent in numerous structural characters. 
