OSTEOLOGY ETC., OP STNGNATHUS PEOKIANUS. 633 



notice on section a dense, somewhat irregularly-shaped mem- 

 brane (fig. 15, Inf. O. S.) lying on the outer surface of the sym- 

 plectic. It appears to correspond to a membrane bone in the 

 adult, which I have named the infra-orbital. 



It will be well to compare the cartilages of the young 

 Syngnathus with those of a typical Teleost, and for this 

 purpose no better choice can be made than the salmon, which 

 has been so admirably worked out by Prof. Parker.^ 



On comparing Parker's fifth stage with my Stage d, the re- 

 semblance will at once be seen. The hyomandibular and sym- 

 plectic elements are not separated. The former is broad and 

 stout, tapering towards the point of articulation with the 

 intevhyal, and a little below this there is a slight bend. In 

 Syngnathus the bend is greater and a little further back, 

 being exactly at the point when the interhyal articulates, i. e., 

 at the point where the two elements meet; and with this greater 

 angulation there is a consequent elongation of the symplectic 

 element. The quadrate element in the Salmon presents the 

 same relations as in Syngnathus, but its metapterygoid 

 portion is much larger, and lies upon the symplectic, forming 

 a buttress to it, while the pterygoid process is shorter. 



The relations, however, of the pterygoid and palatine 

 portions will be more readily recognized on examining an 

 earlier stage of the Salmon. It will then be seen that the 

 palatine portion is originally distinct from the pterygo-quadrate, 

 consisting of a rod bounding the gape above, and extending 

 from the trabeculae almost to the angle of the mouth. Anteriorly 

 it is large and stout, tapering gradually posteriorly, being in 

 fact club-shaped. This is denominated by Parker the second 

 visceral arch, and evidently is the same as the cartilage I have 

 described as the ethmopalatine in Syngnathus. 



InClarias capensis the palatine or ethmopalatine rod 

 is longer than in the Salmon, and overlaps the pterygoid,^ 



1. W. K. Parker, " On the Structure and Development of the Skull in the 

 Salmon," 'Phil. Trans.,' 1873. 



» W. K. Parker, "On the Structure of the Skull in Sharks and Skates," 

 'Trans. Zool. Soc.,' 1878. 



