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



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

 sclieii u. die Anat. der Hasenscharte. 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. 



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

 front of naso-palatine fornuiina. 

 (a) Septal cartilage of nose. 

 (6) 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. 



{h) (/). Integument of upper surface of bill ; {h) its epithelial portion, 



(/) its subepithelial connective tissue. 

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

 Fig. 2. Transverse vertical section of nasal cavi I ies behind naso-palatine forani ina 

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

 bone, 

 (e) Cartilaginous capsule of Jacobson's organ. 

 (ff) Its turbinal cartilage. 

 (/) Nasal cavity. 



(»«) E.xternal portion of premaxillary bone. 

 (l) Large nei've external to nasal cavity. 

 Other letters same as in flg. 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 (ff) glandular tissue in ridge on inner 



vrall of nasal cavity. 

 (n) Nasal bone. 



(s) Palate-process of sujierior maxillary bone. 

 Other letters same as in fie. 1. 



Plate XLIV. 



Fig. 1. Same section as figui-e 2 of Plate XLIIL, but showing Jacobson's organ 

 more highly magnified, drawn with camera. 

 (h) Dumb-bell-shaped bone. 

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

 (h) (b) Its turbinal cartilage. 

 ((■) Layer containing blood-vessels and glandular tissue. , 



(d) Ciliated columnar epithelium. 



(e) Layer of nerve-fibres. 

 (./') Sensory epithelium. 



(ff) Cavity of Jacobson's organ. 

 (i) Septal nasal cartilage. 

 Fig. 2. View of outer wall of lel't nasal cavity, opposite turbinated processes. 



(a) Maxillo-tuvbinal, antei-ior 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. 



