440 JAMES ERNEST KINDRED 



off an angular process, just posterior to which the cartilage 

 articulates with a groove on the dorsal surface of the quadrate 

 portion of the pterygoquadrate. 



Meckel's cartilage of the 8-mni. Sjmgnathus differs in several 

 respects from that of the 6.6-mm. Gasterosteus. In the first 

 place, the curve of the ventral surface of this cartilage in Syngna- 

 thus is concave, while in Gasterosteus it is convex. There is a 

 continuous gradation from the anterior part of the cartilage into 

 the coronoid process in the former, while in the latter, the coro- 

 noid process projects abruptly from the dorsal surface. In 

 Syngnathus the posterior end of the cartilage projects dorsal to 

 the quadrate — a condition not found in Gasterosteus. Of the 

 angular notch and process of Syngnathus, the latter only is 

 present in Gasterosteus. 



A rudimentary inferior labial cartilage is represented by a 

 cellular mass which extends along the dorsal surface of the 

 anterior part of Meckel's cartilage and ends posteriorly in the 

 mandibular fold. It is connected by a bridge of connective- 

 tissue cells with the primordium of the maxillary bone which 

 lies in the supramandibular fold connected dorsally with the 

 lateral surface of the palatine cartilage by fibrous connective 

 tissue. 



The quadrate portion of the pterygoquadrate cartilage starts 

 anteriorly between the posterior end of Meckel's cartilage and 

 the distal end of the symplectic (fig. 1). A narrow bridge of 

 cartilage connects it with the latter element, showing possibly 

 a common origin for the cartilage in this region. In cross- 

 section the quadrate is dumb-bell shaped and lies at right angles 

 to the articular surface of Meckel's cartilage. The posterior 

 part of it projects dorsally as a flattened plate, connected with 

 the posterior end of the palatine cartilage by a densely cellular 

 strand of fibrous connective tissue and separated from the 

 ethmoid cartilage by a fold of the oral cavity (fig. 4). The 

 symplectic cartilage extends along the ventromesial surface of 

 the pterygoquadrate. This cartilage ends posteriorly in the 

 midregion of the orbit with a small posteriorly projecting proc- 

 ess — the metapterygoid process (fig. 1). According to Swin- 



