the Pectoral Girdle in the Pqjefsh. 617 



coracoid, just below its junction with the remainder of the 

 cartilage. 



The most notable change in the coraco-scapular cartihage, 

 however^ is in the scapular region. The scapula (sc) consists 

 of a short stout vertical column^ continuous at its proximal 

 end with the ''intermediate cartilage" {cs) and with the 

 base of the first proximal radial (R) , From its distal end a 

 more slender column passes backward o^er the uppermost of 

 the four foramina to the posterior margin of the cartilage, 

 Avhere it again meets the first proximal radial and is in 

 relation with two of the distal radials. This horizontal part 

 is attached to a projecting ledge on the posterior arm 

 (^. e. behind the stem) of the laminar portion of the clavicle. 

 The scapular process (sc.p) points forward instead of upward, 

 but does not yet take part in the attachment to the clavicle. 

 The scapular foramen or notch has disappeared, being merged 

 in the larger space enclosed between the clavicle and the 

 coraco-scapular cartilage. 



Stage III., 33 mm., about a fortnight after the young 

 fish has left the brood-pouch. — In this stage the skeleton 

 presents a new feature in the commencement of ossification 

 of the cartilages, the surfaces of many bearing a thin coat of 

 clear non-cellular material like the substance of the mem- 

 brane bones. 



Beyond an obvious increase in size and strength ilie post- 

 temporal and the clavicle differ little from the previous stage. 

 The inner branch of the stem of the clavicle has grown 

 toward t!ie jugular plate, but has not yet reached it. 



The appearance of the coracoids at this stage is shown in 

 fig. 3. The coracoid {co) is now distinctly marked off from 

 the remainder of the cartilage, to which it is joined by a 

 thin neck. The precoracoid process [pr.p), directed slightly 

 outward, is very short in comparison with its thickness, and 

 has become practically the anterior part of the coracoid (co). 

 At its anterior end the precoracoid process is attached to the 

 inner branch of the stem of the clavicle {i.cl). The post- 

 coracoid process [pt.p), slightly larger than in stage II., is a 

 small somewhat conical tubei'osity at the posterior end of 

 the coracoid, behind and below the neck connecting it with 

 the remainder of the cartilage. This process is ossified, and 

 from its base the first traces of ossification extend forward 

 over the surface of the coracoid toward the precoracoid 

 process. 



The anterior border of the coraco-scapular cartilage is 

 curved inward above to the point where it is attached to 

 the clavicle through the medium of the anterior part of the 



