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MR. E. PHELPS ALUS, JUN., OX 



dorsal ly along the external surface of the latter cartilage. This 

 crescentic" cartilage and the nasal-fold process of the cartilage fg 

 thus seem to both be chondrifications of this fibrous tissue, one 

 of them related to the cartilage d (posterior upper labial) and the 

 other to the cartilage fg. 



The cartilage fg is thus a strongly curved cartilage which 

 encircles the lateral half of the fenestra nasalis, lying against 

 the external, and not the internal, surface of the edge of the 

 fenestra, and it either sends a process into the ridge on the 

 internal surface of the naso-labial fold, or becomes secondarily 

 fused with a cartilage that is developed independently in that 

 ridge. The lining membrane of the nasal capsule is not attached 

 to this cartilage /}/, as it is to the cartilage kn (ala nasalis), lying 

 wholly internal to it. The cartilage is capable of a swinging, 

 dorso- ventral motion around a line passing through its two 

 points of attachment to tlte chondrocranium, the cartilage 

 passing backward and forward across the outer, and not the 

 inner, surface of the lateral edge of the fenestra, nasalis. The 

 posterior one of these two motions is impressed upon it by the 

 musculus levator anguli oris anterior of Vetter's (1878) de- 

 scriptions, acting both through its own tendon and the long and 

 slender ligament called by Luther (1909 b) the levator carti- 

 laginis prselabialis, the contrary motion apparently being caused 

 in part by the simple elasticity of the parts, and in part by the 

 action of the musculus labialis posterior. The musculus labialis 

 anterior, which is attached by one end to the dorso-anterior end 

 of this cartilage and by the other to the cartilage cl (posterior 

 upper labial), would seem to exert its action on the latter rather 

 than on the former cartilage. 



Hubrecht says that the process a of Gegenbaur's descriptions 

 of the Selachii, together with that part of the edge of the nasal 

 capsule that, in those fishes, bounds the mesial edge of the 

 postero-mesial nasal aperture, corresponds to the cartilage kn of 

 Chimcera, this latter cartilage thus being considered by him to be 

 cut oft" from the outer edge of the nasal capsule, and its process n 

 to correspond to the process a of the Selachii. The cartilage fg 

 of Chimcera is said to correspond to the process ft of Gegenbaur's 

 descriptions of the Selachii, the cartilage e of Chimcera to 

 represent the anterior upper labial of the Selachii, and the 

 cartilage I to be a remnant of that part of the ala nasalis that 

 primarily connected the cartilages kn andy*(/. 



Both Fiirbringer (1903) and Luther (1909 b) apparently accept 

 Hubrecht's conclusions regarding the homologies of these several 

 cartilages of Chimcera ; but Luther nevertheless, calls the car- 

 tilage fg a premaxillary cartilage, which must mean that he 

 considers it to be a labial and not a, Nasenfliigelknorpel, and 

 he neither mentions, nor shows in his figures, the cartilage e. 

 Vetter (1878), who knew of Hubrecht's work only by title, 

 describes as a. premaxillary cartilage a, cartilage that must be 

 the cartilage fg of Hubrecht's descriptions, but he makes no 



