1906.] ON ABNORMAL TROUT EMBRYOS. 449 



EXPLANATION OF PLATE XXXL 



Fig. 1. Ci'clopean Trout of type A, seen from left side. 



Fig. 2. Transverse section through frontal process of the same cj'clopean Trout, 



showing the small approximated olfactory pits (O.) and the reduced olfactory 



capsular cartilage (C.). 

 Fig. 3. Transverse section through posterior part of cerebral lobes of same, showing 



the cerebral lobes (F.B.) intimately united along their inner surfaces, and 



the pineal bodj^ Pin. The central cavity of the brain {C.F.B.)is not dropsical, 



and the cerebral lobes are almost normal in size. 

 Fig. 4. Section passing through mid-brain, posterior part of eye, and mouth of 



same : — 



O.L. Optic lobes. 



O.N'. „ nerve. 



JRec. „ recess. 



S. sup. Rectus superior. 



M.inf. ,, inferior. 



GL. Ch. Choroidal gland. 



Bet. Retina. 



M. Mouth. 

 T. Tongue. 

 C. So. Supra-orbital cartilages. 

 Tr. Cr. Trabeculse cranii. 

 Fl. qt. Palato-quadrate. 

 Meek. Symphysis of lower jaw. 

 L. Lymph space. 



Fig. 5. Section through mid-brain of embryo belonging to type B, showing obli- 

 teration of the ventral groove which should pass down into the stalk of the 

 infundibulum. 



Fig. 6. Section through retina of eye described on page 446, showing failure of deve- 

 lopment of the optic nerve and of the choroidal fissure. Pg., pigment la3'er ; 

 Bet., retina ; f., a few fibres, which do not, however, pierce the sclerotic. 



4. Notes on Supernumerary Eyes, and Local Deficiency and 

 Reduplication of the Notocliord in Trout Embryos. By 

 James F. Gemmill, M.A., M.D. 



[Received February 20, 1906.] 

 (Plate XXXIII. *) 



(A) Supernumerary Eyes in Trout Emhyros (fivo specimens). 



The first specimen is in some respects unique in vertebrate 

 teratology. My attention was directed to it by the presence of 

 an interruption or cleft in the right upper jaw, producing the 

 appearance of a right-sided harelip in what seemed to be, in other 

 respects, a normal newly-hatched Trout embiyo. On cutting serial 

 sections, I found that a small additional eye lay at the bottom of 

 this cleft, in the roof of the mouth, to the right side of the middle 

 line, in the same transverse plane as the normal eyes. The 

 additional eye is embedded in confused muscular tissue, has a 

 well-developed lens, a small retina, no choroidal fissure and no 

 choroidal gland. Its optic nerve is represented by a small bundle 

 of fibres which sweep over the edge of the retina to join the right 

 normal optic nerve (fig. 1, PI. XXXIII ). The retina is small 

 and elongated antero-posteriorly. The pigment- layer is present 

 as such only in the posterior half of the retina. Anteriorly, the 



* For explanation of the Plate, see p. 452. 



