LABIAL CARTILAGES OF RAIA CLAVATA. 
99' 
English authors. J. Muller (1834) also did not consider this 
nasal-flap cartilage to be a labial cartilage, and he called it 
the inner Nasenflugelknorpel. 
This nasal-flap cartilage of Eaia clavata has the shape 
shown in the accompanying figures, and it is connected with 
what Gegenbaur calls the anterior process of the correspond- 
ing ala nasalis by the dermal and connective tissues of tho 
nasal flap. At its anteror (aboral) corner there is, on 
one side of the head of my one specimen, a small and 
independent bit of cartilage. In about the middle of the 
postero-mesial edge of the cartilage there is a curved 
incisure, and slightly lateral to the bottom of this incisure,, 
and parallel to the edge of the cartilage, there is a ridge on 
the internal surface of the cartilage. The mesial surface of 
this ridge is flat and slopes gradually to the edge of tlie- 
cartilage, and, on either side of the incisure, it rests upon and 
is firmly bound to the posterior upper labial of GegenbauEs 
descriptions, this contact with the latter labial being 
particularly large and strong anterior (aboral) to the incisure. 
The lateral (absymphysial) surface of the ridge is abrupt 
and curved, and forms the mesial (symphysial) boundary 
of the nasal-flap furrow, thus marking the base of the nasal 
flap. The nasal-flap cartilage thus extends mesially beyond 
the base of the nasal flap into the general tissues on the 
ventral surface of the head, but it in no place reaches or 
touches the palato-quadrate, being everywhere separated 
from it either by the so-called posterior labial cartilage or 
by the nasal-flap furrow. The incisure in the postero-mesial 
edge of the nasal-flap cartilage arches over the posterior 
(oral) end of a short section of the nasal latero-sensory canal 
(Garman, 1888) that is directed antero-posteriorly. 
The posterior upper labial of Gegenbaur's descriptions 
above referred to, is the only labial found in either Eaia 
clavata or Eaia radiata, and it will accordingly be called,, 
in the following descriptions, the upper labial, or simply the 
labial. It consists of two broad and approximately parallel 
portions connected by a narrow neck of cartilage which 
