LABIAL CARTILAGES OF RATA CLAVATA. 
95- 
The So-called Labial Cartilages of Raia 
clavata. 
Bj 
Edward Pholps Allis, junr., 
Menton, France. 
With Plate 6. 
Gegenbaur (1872), in his classical work on “ Das Kopfskelet 
der Selachier,” describes (1. c., p. 216), in Raia (species not 
given) and Raia vomer, two cartilages which he considers 
to be the homologues of the labial cartilages of Selachii. In 
Raia (species not given), which is the one first described, one 
of these two cartilages is shown lying definitely nearer the 
anterior end of the ventral surface of the snout than the 
other cartilage, and, doubtless because of this, the former 
cartilage is called the anterior upper labial and the other 
the posterior upper labial. The so-called anterior labial lies,' 
however, farther from the symphysis of the upper jaw and 
farther from the upper edge of the mouth than the so-called 
posterior one, and if the mouth were terminal it would be 
the posterior instead of the anterior cartilage. Doubtless 
because of this, Gegenbaur says (l.c., p. 218) that it is 
evident that the so-called anterior upper labial of the Batoidei 
corresponds to the posterior upper labial of the Selachii, and 
the posterior upper labial of the Batoidei to the anterior 
upper labial of the Selachii. The posterior (oral) edge of the 
posterior labial is shown (1. c., PI. 17, fig. 1) in contact, its 
full length, with the palatoquadrate; its anterior (aboral) edge 
is said to be bound to the posterior (oral) edge of the anterior 
