384 "• "• P<^i^LAUi». 



The cartilaginous toriiiinal portions of the prepalatine piece (Pre- 

 pal.) are shown in the figures, the part round about the articulation 

 with the preorbital process being replaced by bone. The prepalatine 

 cartilage reaches almost to the tip of the snout. A small round block 

 (m.v.s.) between the ends of the prepalatine cartilages in the model 

 represents, in a very diagrammatic fashion, the premaxillary piece 

 and rudimentary median support of the velum. 



The Meckelian cartilage (Mck) has an inverted T-shape, the arms 

 of the T being long. The posterior arm does not reach the quadrate, 

 the quadrato-mandibular articulation being formed by bone. The 

 upper process is the coronoid process {Proc. cor.) which bears the 

 long and large procartilaginous coronoid piece {Cot: p.), which is con- 

 tinued into a tentacle combining characters of maxillary and coronoid 

 tentacle [Mx. t.), in that it is continuous with the coronoid piece, and 

 also supported by the maxilla , which is attached to the end of the 

 prepalatine cartilage. The tentacle is directed outwards and back- 

 wards. The anterior arm of the Meckelian cartilage is the mento- 

 meckelian process (If. mcL), which is very far from reaching its fellow 

 of the opposite side. I am inclined to think that it has not, at an 

 earlier ontogenetic stage, extended further. 



In the fleshy lower lip, there is a huge block of procartilage') 

 (Ment, p.), with a projection directed posteriorly, while medially and 

 somewhat below this block may be seen on each side the mental 

 tentacle {Ment, t.), wliich is actually supported by a lamina of pro- 

 cartilage, lying superficially below the dentary bone. This supporting 

 lamina is of considerable extent. 



A su])niandibular tentacle {Subm. t.) lies below the coronoid pro- 

 cess, also with a superficial supporting lamina of procartilage. 



A stylohyal (Sty. hy.) bears the ceratohyal (Hy.) which is massive 

 posteriorly. The thickened anterior end bears a hypohyal piece. 



.Model of Silurus (Figs. 3, 4). 



Sections 15 /li thick. Every 3rd section drawn, with magnification 

 28 (Zeiss ()c. 2, Obj. aa). Height of drawing above table 19 cm. 

 Wax plates 1 mm thick. Model, reconstructed as far as middle of 

 horizontal semicircular canal (on one side), 11 cm long and 15 broad. 



The drawings for this model were taken from sections belonging 

 to Prof. DoHRN, which he kindly allowed me to use. The cartilage was 

 at its maximum development, no replacement by bone having occurred. 



1) Better termed Extramental. 



