1010.] AXD uioLoGV OF Trip: LAitnicii ci'TAC'EA. 78:1 



the glottis is divided into a riglit half for tlie pnssagc of food and 

 a left half for respiration. This arraugenieut gives an asym- 

 metrical form to the nasal regions of the skull. 



Pouchet and Beauregard*, in their admi]-ahle memoir on the 

 anatomy of the Sperm Whale, refer to the pipedike epiglottis as 

 being asymmetrically jilaced ; but they state that it was situated 

 on the right side of the pharynx, whereas in both the specimens 

 of Phj/seter seen at Innishkea the pipe was undonbteilly on the 

 left side. These authors appear to have attached no signiticance 

 to the position of the epiglottis as bearing upon the iisymmetry of 

 the skull. 



VI. Notes ox the Species. 

 1. Bal.exoptera musculus LinnjBust. 



The length, form, and proportions of all the specimens seen were 

 in accordance with previous desciiptions of the species. 



Colotw. There appeared to be two colour-types in this species, 

 distinguished by the colour of the dorsal surface. In the moi'e 

 common type the colour of the dorsal surface was bluish black ; 

 in the other variety the dorsal surface was brownish black, 

 almost sepia. This fact has been noticed by Mr. HaldaneJ, who 

 attributes the difference in colour to a liglit-eftect ; but it was 

 sufficiently marked in all the individuals landed during my visit 

 for them to be placed in either one or other of the two groups. 



The asymmetrical colouring of the face was remarkably constant 

 in all the specimens. On the right side the outer edge of the 

 beak was white or light grey ; on the left side the beak was entirely 

 bluish black or sepia in colour, according to the variety which the 

 individual belonged to. The anterior third of the baleen plates 

 on the right side were invariably white, the remainder on that 

 side being dark grey or black on the outer halves of the plates 

 and becoming lighter in colour towards their inner edges. On 

 the left side all the baleen plates were similar to the posterioi- 

 plates of the right side. The bristles were invariably white all 

 round the mouth, and not black as stated by Mr. Collett§ in his 

 synopsis of the four northern species of Halnnopiera. The lower 

 jaw was white on the right side, and bluish black or sepia, on the 

 left side. The whole underside of the body, the right lower jaw, 

 the inner side of the paddles, and the under side of the flukes of 

 the tail were white in all cases. The roof of the mouth consists 

 of a broad oval margin of white bristles surrounding a narrow 

 strip of pink palate, and below, a pink tongue covered with dark 

 grey mottling. Every specimen had whitish oblong spots dis- 

 tributed over the dark parts of the body, identical, except in 



* Pouchet et Beiiurcgavd , Nouvclles Archives lUi Museum (Paris), 3 ser. vol. iv 

 1892, p. 59, pi. iii. 



t Known also as B. pJi/fsalua Fahiieius, B. roi-'jnal Laeepeile, I'hi/salas anti- 

 ifiioniin (Jniy. 



X Haldaue, Annals of Scottish Nat. H'st. 190S, p. 70. 



§ CoUetl, I'roc. Zool. Soc. 1880, p. 2(35. 



51* 



