ieee EDWARD PHELPS ALLIS, JR. 
of the capsule. It is slightly concave on its dorso-lateral sur- 
face, the concavity being bounded dorso-posteriorly by a slight 
eminence on the cartilage and ventro-anteriorly by two sharply 
pointed processes of the cartilage. The rounded eminence is 
bound by ligamentous tissues to a corresponding eminence on 
the internal surface of the cartilage ‘fg’ of Hubrecht’s descrip- 
tions, and the two pointed processes support the tissues of the 
V-shaped valvular surface of the valvular process. Ventral to 
those pointed processes the cylinder is slit its full length, the cut 
edges of the cartilage supporting the longitudinal valvular sur- 
face and its valve-seat. The alar cartilage projects slightly 
into the nasal capsule, the inner lining membrane of which is 
firmly attached to it. 
The conditions in Chimaera are thus, as already stated, 
markedly different from those in the Plagiostomi, but it would 
nevertheless seem as if they could have been derived from those 
in certain of the latter fishes. In Miiller and Henle’s (41) 
figure of Chiloscylliium punctatum, reproduced in the accom- 
panying figure 4, a dermal fold is shown which encircles the 
lateral edge of the antero-lateral nasal aperture; it may be 
referred to as the nasal fold in order to distinguish it from the 
nasal flap. The antero-mesial end of this fold lies anterior 
(aboral) to the nasal flap and the related process a of the ala 
nasalis. Posterior to this fold, and lying slightly deeper than it, 
is the flap-seat and the related process 6 of the ala nasalis, and 
posterior to the flap-seat there is a labial fold, the supralabial 
furrow and the furrow of the nasal fold apparently being con- 
tinuous at their adjoining ends. In this fish the long axis of 
the fenestra nasalis has certainly rotated a certain distance in 
the same direction that it rotates in other Plagiostomi, and if 
this rotation were to be continued until the axis of the fenestra 
had acquired the position that it has in Chimaera, and approxi- 
mately has in Heterodontus, and if each of the two nasal apertures 
were to follow that end of the axis of the fenestra to which it is 
related until it came to lie directly external to it, as the two 
apertures approximately do in Chimaera, the antero-lateral 
aperture would pass internal to the nasal fold, and the nasal 
