102 
EDWARD PHELrS ALLIS. 
that cartilage, but, excepting where it crosses the mesial 
portion of the labial, there is no noticeable groove to mark 
its course. In my specimens of Raia radiata, because 
of the marked twist in the neck of the labial, the canal 
there has markedly the appearance of lying on the internal 
rather than on the external surface of the labial. In Raia 
cl a vat a some of those branches of the nervus buccalis 
lateralis that innervate the organs of the canal perforate 
the labial, but most of them pass over the anterior (aboral) 
edge of the labial and then turn posteriorly (orally) across 
its external surface. They always lie internal to the nasal- 
flap cartilage. 
In Raia batis Ewart (1892) shows two loops in the nasal 
latero-sensory canal. No such loops were found in Raia 
clavata, and it is probable that they are exaggerated in 
Ewart’s figure, the loops simply representing points where 
the canal follows bends or twists in the labial such as I find 
in Raia radiata. 
In my specimens of Myliobatis the nasal-flap furrows are 
so wide (deep) that they nearly meet in the median line, a 
narrow “frenulum” (Gegenbaur) there alone separating them. 
In correlation with this extension of the nasal-flap furrows 
the nasal-flap cartilages have been carried toward the median 
]ine, and are there separated from each other by only a 
narrow space in which lies the small median bit of cartilage 
that Muller (1834) describes as the “ Trager der Nasen- 
fliigelknorpel.” The nasal-flap cartilage, called by Muller the 
inner Nasenfliigelknorpel, has the triangular shape shown by 
that author in his figure of Myliobatis aquila (1. c. PI. 9, 
fig. 13), bufc it is more deeply fimbricated in my specimens 
than shown by Muller. The ala nasalis is as shown in Muller’s 
figure. The nasal-flap furrow lies internal to both these 
cartilages. The nasal latero-sensory canal runs internal to 
the nasal- flap furrow, and then outward and forward (aborally) 
in the frenulum to meet and fuse, in the median line, with its 
fellow of the opposite side. In one of my specimens the canal 
is enclosed in the ventral edge of a strip of cartilage that has 
