584 ON THE ANATOMY OF ORNITHORHYNCHUS. [NoV. 17, 



16. KoLLiKER, Dr. Th. — XJeber das os intermaxillare des Men- 

 scheu u. die Anat. der Hasenscbarte. Nova Acta Acad. Cses. 

 Leop.-Car. xliii. p. 325. Halle, 1882. 



17. ScHWiNK, Dr. J. — " Ueber den Zwischenkiefer und seine 

 Nachbarorgane bei Saugethieren." Miinchen, 1888. 



EXPLANATION OF THE PLATES. 

 Plate XLIII. 



Eig. 1. Transverse vertical section of nasal cavities behind nostrils and in 

 front of naso-palatine foramina. 

 (a) Septal cartilage of nose. 

 (h) Cartilage in roof of nose. 



(c) Cartilage in floor of nose just external to cavity containing Jacobson's 



organ. 



(d) Dumb-bell-shaped bone. 



(e) (/) (ff). Three compartments of anterior part of nasal cavity. 



(k) (^). integument of upper surface of bill ; (A) its epithelial portion, 



(?) its subepithelial connective tissue. 

 (k) (J). Integument of under surface of bill. 

 Fig. 2. Transverse vertical section of nasal cavities behind naso-palatine foramina 

 and through about middle of posterior swelling of dumb-bell-shaped 

 bone, 

 (e) Cartilaginous capsule of Jacobson's organ. 

 (g) Its tui'binal cartilage. 

 (/) Nasal cavity. 



(m) External portion of premaxillary bone. 

 (I) Large nerve external to nasal cavity. 

 Other letters same as in fig. 1. 

 Fig. 3. Transverse vertical section of nas;il cavities behind Jacobson's organ 

 and in front of turbinated processes. 

 (v) Vomer, 

 (o) Olfactory nerve-fibres and (g) glandular tissue in ridge on inner 



wall of nasal cavity. 

 (n) Nasal bone. 



(s) Palate-process of superior maxillary bone. 

 Other letters same as in fig. 1. 



Plate XLIV. 



Fig. 1. Same section as figure 2 of Plate XLIII., but showing Jacobson's organ 

 more highly magnified, drawn with camera. 

 (k) Dumb-bell-shaped bone. 



(a) (a) Cartilaginous capsule of Jacobson's organ. 



(b) (b) Its turbinal cai-tilage. 



(c) Layer containing blood-vessels and glandular tissue. 



(d) Ciliated columnar epithelium. 



(e) Layer of nerve-fibres. 

 (,/') Sensory epithelium. 



(g) Cavity of Jacobson's organ. 

 («') Septal nasal cartilage. 

 Fig. 2. View of outer wall of left nasal cavity, opposite turbinated processes. 



(a) Maxillo-tiirbinal, tintenor extremity not shown. 

 ■ (1) (2) (3) (4) (.5) are the five ethmo-turbinals. 



(b) Nasal cavity behind the turbinals. 



(c) indicates position, on under surface of specimen, of the posterior 



horny plate. 



