741 



ated bj' tlie jugular vein. The neuromast on the medial wall jiiRl 

 projects witli its posterior niaroiii from llie vestibiiliiiri. 



I was not successful in finding tlie snpplving nerve. Perliaps it 

 is owing to the intensely stained connective tissne capsnle. which 

 is more developed than in the largest of the examined embryos of 

 Acanlhias. In the 225 m.in. long embryo the organ was so badly 

 preserved, that nothing of importance can be mentioned '). 



'Ó. Fenestr'a vestlbuH. 



In the 63 m.m. long embryo of' Heptanchns, the attachment of 

 the hyomandibular to the anditory capsule is brouglit about by a 

 thin laver of connective tissue, wherein I can find no cavity of 





Fig. 4. Lateral surface of the model 

 of a disk from the cartilage of the 

 regio olica of an embryo of Heptanchus 

 eiiiereus. The disk is placed in such 

 a position that a part of the anterior 

 surface with the canalis semich-cularis 

 lateralis, is just visible, and the fenestra 

 veslibuli is not covered by the upper 

 part of the hyomandibular. 



') Before the translation of this paper, the work of Vitau (Anat. Anzeig. 1911 

 and 1912) had escaped my notice, and I am indebted to Dr. Benjamins of Utrecht 

 for having called my attention to it. As lie remarks, this paratympanic organ in 

 birds must be the homologue of the spiracular sense organ. An interesting referate 

 of the works of Vitali on this organ by Ruffini "Sull organo nervoso para- 

 timpanico di G. Vitali od organo del volo degli uccelli" is to be found in 

 ■'Archivio Italiano di Otologia Rinologia e Laringologia" publ. by üeadenigo. 

 Vol. 31, 1920. 



