14 OSTEOLOGY OF SCOMBROID FISHES 



The inferior pharyngeals are broadly in contact but are not co-ossified. 

 Just in front of them the ceratobranchial of the fourth arch becomes 

 compressed and as thin as paper. The hypobranchial of the last arch 

 is missing. Two basibranchials are ossified. 



The clavicle extends far below and anterior to the lower end of the 

 hypocoracoid, as it does in members of the family Scombridae. Its lower 

 end is broad and rounded. At the middle of its length a thin, vertical 

 plate extends inward, nearly meeting its fellow of the opposite side, 

 and forming a partition behind the branchial cavity. At the outer 

 edge of the clavicle are two triangular projecting points, which show 

 prominently just under the gill cover of the undissected specimen. A 

 process is developed backward from the upper edge of the clavicle for 

 the suspension of the postclavicle. 



The hypocoracoid is small, and arches away from the clavicle to 

 rejoin the latter at its lower end, inclosing a space between as is usual. 



The hypercoracoid is pierced at its middle by a large, round fora- 

 men, but this element sets so far behind the clavicle that the clavicle 

 appears to bound the foramen at its anterior edge when viewed from 

 the outer surface of the shoulder girdle. 



The actinosts increase in size downward, and have a small hole 

 between each pair. The upper edge of the pectoral works directly on the 

 edge of the hypercoracoid. Two of the actinosts are on the hypercoracoid 

 and two on the hypocoracoid. 



The postclavicle is in two parts the lower part lance-head-shaped 

 and a little wider than usual. 



The post-temporal is rather widely forked, and joined to the cranium 

 without the intervention of ligaments on either fork. The supraclavicle 

 is present below it. 



The pelvic girdle is attached closely between the clavicles. From 

 the base of each ventral spine a long spine projects forward just beneath 

 the skin of the breast, and is stiffened above by a wide web of bone 

 between it and the main part of the girdle, thus inclosing between them 

 a deep cavity at the front of the girdle. Posteriorly above the ventral 

 fins each part of the girdle sends back a stout spine which is suturally 

 united with its fellow into a single spine. 



At the base of each anal and dorsal ray is an exceedingly large 

 baseost. Each of these is firmly united by suture to two interspinous 

 rays, so that each of the latter bears two halves of a baseost. These 

 project outward between the rays making the steps or notches into 

 which the rays fit that are referred to at the beginning of this paper. 



