Prof. Owen's Description of the Lepidosiren annectens. 361 



cesses of the right maxiUary dental plate, c. The corresponding 

 processes of the left mandibular dental plate, e. A bristle in- 

 serted into the right olfactory sac, which opens upon the upper 

 lip. é . The left olfactory sac laid open, exposing the double series 

 of olfactory laminae. 

 Figg. 3 & 4. Brain and organ of hearing of the Lepidosiren, twice natural size. 

 a. a. Cerebral hemispheres, b. Optic lobe. c. Medulla oblongata. 

 d. Cerebellum and fourth ventricle, e. Pineal gland. /. Bilobed 

 pituitary body, forming the floor of the third ventricle, g. Mam- 

 millary body. h. Olfactory nerves. /. Optic nerves, k. Carti- 

 laginous wall of acoustic chamber or labyrinth. I. Sac and nerve 

 of smaller otolithe. ?«. Sac and nerve of greater otolithe. ?i. Se- 

 micircular canals, o. Fifth pair of nerves, p. Eighth pair of 

 nerves. 



5. Brain of the Menopoma. (From Meyer, Analekten fur Vergleichende 



Anatomic, tab. vii. fig. 5.) 



6. Brain of the Menobranchus. (Ibid. tab. vii. fig. 6.) 



Both these figures are of the natural size. 

 The same letters indicate the same parts as in Figg. 3 & 4. 

 ~ . a. Œsophagus. b. Stomach, c. Intestine. /'. Liver, g. Gall-bladder. 

 h.h. Kidneys. /. /. Ureters; both are reflected downwards and 

 outwards to show, h. Allantoid bladder. /. /. Ovaria. m.m. Ovi- 

 ducts, n.n. Anterior apertures of the same. 

 These parts are figured as seen from behind. 



3 B 2 



