ZOOLOGY: E. P. ALUS 
75 
fold of the secondary upper lip and is not even crossed by that fold. 
This edge of the nasal flap thus does not form part of the secondary 
upper lip of the fish. 
Cartilages are usually found developed in relation to the secondary 
lips of the Plagiostomi and Holocephali, and bones, with or without 
teeth, in the Teleostomi, the bones in the upper lips of the latter fishes 
forming a premaxillo-maxillary dental arcade which lies external to, 
and concentric with, the primary palatoquadrate, or so-called vomero- 
palato-pterygoid arcade. 
In the Teleostomi, Holocephali and Dipneusti a dermal fold may be 
found lying aboral to the secondary upper lip. 
In the Teleostei and Holostei this fold lies along and encloses the ven- 
tral edge of the lachrymal bone alone, or the ventral edges of that bone 
and one or more of the suborbital bones, and some part of the dorsal 
edge of the maxillary bone passes upward internal to the fold. The fold 
may accordingly be called the supramaxillary fold, for although it is, 
in these fishes, definitely related to the lachrymal bone, it is not so re- 
lated to that bone in the Holocephali and Dipneusti. The fold, in 
the Teleostei and Holostei, is not continued forward in relation to the 
antorbital and dermal ethmoid bones, those bones being developed in 
relation to the antorbital section of the buccalis latero-sensory canal, 
the fold apparently being restricted to the suborbital section of that 
canal. In the Anacanthini, because of the marked anterior extension 
of the lachrymal bone, the fold is carried forward between the nasal 
•apertures and the upper edge of the mouth, and is there continuous, 
in the median line, with its fellow of the opposite side; this apparently 
being a specific character of these fishes. 
In the Holocephali and Dipneusti the supramaxillary fold passes 
aboral to the nasal apertures, and in these fishes the buccalis latero- 
sensory line passes aboral instead of oral to those apertures, and neither 
lachrymal, antorbital nor dermal ethmoid bones are developed in re- 
lation to it. In Chimaera the fold encloses the outer ends of a series 
of ampuUary tubules, the external openings of these tubules lying near 
the edge of the fold and representing the places of origin of the related 
ampullary organs (Allis,^); and the coalesced folds of opposite sides 
form a semicircular line which circumscribes the nasal apertures, the 
upper lips, and the related naso-labial folds. In Ceratodus this fold 
has this same relation to the nasal apertures and the secondary upper 
lips, but it has here become a tertiary upper lip, and that band of the 
external surface of the head that lies between it and the secondary upper 
lip has been added to the secondary cavity of the mouth. The two 
