652 ALLIS. [Vor. XII. 
With the anterior and larger portion of the proximal end of 
the second epibranchial the infrapharyngobranchial (JPB.//.) 
of the arch articulates. It is a large, somewhat rectangular 
piece, as long as, or slightly longer than, the epibranchial of the 
arch, and lies inclined in the opposite direction to that piece ; 
that is, with its anterior edge at a much higher level than 
the posterior one. It is capped on both ends with cartilage, 
the cartilage on the proximal end extending outward along the 
anterior edge of the piece for about one half its length. At 
this outer or distal end it articulates with the first epibranchial, 
its edge overlapping dorsally the edge of that piece. 
The third epibranchial (2B.///) is a short, nearly straight 
piece deeply grooved on its dorsal surface and with a rounded 
proximal end by which it articulates with the outer, posterior 
cartilaginous edge of the third infrapharyngobranchial, and 
with the anterior corner of the fourth epibranchial. Distal to 
this last articulation the proximal cartilaginous cap of the 
piece extends outward along the posterior edge of the element, 
for about one half its length, and ends in a strong, upturned 
process which much resembles the corresponding process on 
the second epibranchial plus the suprapharyngobranchial of 
that arch. This cartilaginous posterior process, in some speci- 
mens, becomes independent of, and not connected by cartilage 
with the proximal cartilaginous cap. From its posterior edge 
at its base the ligamentum interarcuale dorsale III (“d.///) 
arises and is inserted along the anterior edge of the bony por- 
tion of the fourth epibranchial. Between this ligament and 
the articular ligament there is, as on the other arches, an 
opening through which descends the pharyngeal branch of the 
third vagus. 
The upper pharyngeal bone (/P8.///) is a large piece lying 
perpendicular to the direction of the arches, rounded in front 
and pointed behind, and may be considered, with van Wijhe, as 
the third infrapharyngobranchial alone, or, and perhaps more 
properly, as the fused infrapharyngobranchials of the third and 
fourth arches, and possibly of the fifth arch also. It is mainly 
cartilaginous, the bony portion of the piece being a circular 
ossification lying at its anterior, outer edge and entirely sur- 

