4:^2 ^h-. IT. Day 07i the 



obioncr facet of cartilage for articulating with the pedicle of 

 the suspensoriiuii.'' 



Svviunerton notes that Smith Woodward has discovered 

 that in Z^'p/Wo^us there is a stout process of the metapterygoid 

 wliicli bears a large facet which may have articulated with a 

 lateral element in the cranium. ISwinnerton believes that 

 this process is the homologue of the pedicle of the palato- 

 quadrate bar in Lepidosteus. After a consideration of Smith 

 AVoodward's desciiption and figures (i o) it becomes difficult, 

 however, to suppose that the "lateral element in the 

 cranium," mentioned by him, can represent the basipterygoid 

 processes as in Lepidosteus, since in Lepidotus he figures 

 well-developed basipterygoid processes of the "' paraspheuoid" 

 Avhich apparently liave sutnral terminations, and therefore 

 could not have been apposed to the facet which is found on 

 the anterior process of the metapterygoid, though there can 

 be little doubt that these basipterygoid processes united with 

 the pterygoid region. 



Watson has shown that Megalichthys has similar processes 

 from the basisphenoid region of the basis cranii, and that 

 these have a sutural union with the pterygoid region, and 

 that Loxomma and Pteroplax also po.^sess exact!}'" similar 

 jnocesses of the " basisphenoid " articulating with the same 

 region. In the present specimens the basipterygoid or 

 anterior lateral processes bear articulating faces, and, we may 

 take it, correspond with those of Lepidosteus, Lejjidotus, and 

 Megalicldhys amongst fishes, and with the similar processes 

 of the basisphenoid region as described by Watson in 

 Loxomma, Fteroplux, and Batrachiderpeton amongst the 

 fossil Amphibia, and in which the articulation is by facet 

 with the pterygoid region. 



It appears, then, that the additional pedicular articulation 

 of the palato-quadrate region with the trabecular is simply 

 continued in an homologous form in the union of pterygoid 

 region with the basipterygoid processes, a union by tacet or 

 suture. 



Swinnerton notes tliat in the Selachii also there is a 

 constant recurrence of this pedicle of the palato-quadrate 

 region, pointing back to an ancestor " which certainly 

 possessed that feature." 



Iti that case, on the evidence brought forw^ard above, we 

 have a line passing from the Selachii tlirougii the |niniitive 

 Teleostomes to the primitive An)phibia and lieptilia, on 

 which line there is this characteristic j)edicular connexion 

 between the palato-quadrate region and the trabeculje of the 

 chondrocranium, and hence these groups all agree in possess- 



