45 



a slight sigmoid curve, and its hinder part overh\ps tlie lower lip, and extends so far back as almost to come beneath the 

 anterior angle of the eye. which lies 2 centini. above. The external nasal aperture lies in the same transverse plane as 

 the anterior part of the eye tissure. 



The pectorals, about 9 centim. in length, amount to between Vs and 'A of the length of the body (in the younger 

 male, to Ve) and the width is a little more than half the length. They are of the characteristic spatulate form. 



The dorsal fin, 42 millim. in height and 61 millim. broad at the base, amounts to about Vis of the length of the 

 trunk. Its anterior margin is convex, its posterior deeply concave; its base is not sharply deiined. 



The post-anal segment is very much compressed, and has ventral and dorsal keels. The tail is about 140 milHni. 

 broad, its length being contained between 4 and 5 times in that of the body. 



The somewhat constricted insertion of the umbilical cord is 18 millim. broad. The penis lies midway between the anus 

 and the navel, and projects considerably from the prepuce; there is only an indication of the fold of skin into which it is 

 subsecjuently withdrawn. About halfway between the anus and the penis, but rather nearer to the anus, are 2 small 

 openings, which nmst be interpreted as the rudimentary mammæ masculinæ. 



The colour in this embryo is more sharply defined than in the previous one. The darkest shade is found over the 

 head and the back of the neck as far as the dorsal fin; the next, round the eye and the borders of the pectorals. The 

 rest of the coloured portion is not quite as dark. The black line on the upper front part of the back, which was mentioned 

 in the description of the 40 centim. long fætus, is here also very distinct, though somewhat fainter in its foremost part. 

 On both sides of the dorsal fin, especially at the posterior end, the colour is of a lighter shade, corresponding to the 

 purple patch observed on the full-grown animal. The yellowish white, wedge-shaped patch in which the anus and the penis 

 are situated, is separated from the hindmost side-patch by a dark wedge-shaped patch running forwards. There is a little 

 pigmentation on the preputium and on the fold of skin round it, as also a little on the umbilical cord nearest the insertion. 

 The distribution of the white colour includes, as in the 40 centim. long fætus, the border of the upper jaw, the whole 

 of the lower jaw. the tiiroat region to a little above the shoulder joint, and the ventral surface; on the last-named, from the 

 pectorals to some distance beyond the navel, the yellowish white part is very narrow, but farther on, it enlarges to form 

 the characteristic oval side-patch, while the white colour in the median line forms the tongue-shaped part, in which the 

 anus and the genitalia externa lie. Almost the whole of the inferior surface of the tail fin, with the exception of the edges 

 and the extreme points of the flukes, is yellowish white, as is also the extreme end of the ventral ridge. The foremost 

 light side-patch is bounded in front and below by the black part round the eye. It is of an elongated oval shape, and 

 extends as far as the shoulder joint. Round the posterior axillary border there is a thinly coloured region of yellowish 

 white mixed with greyish blue, while the dark pigment beneath the pectorals forms a forward-pointing, wedge-shaped patch. 

 There is also a rather darker shade on each side of the yellowish white lower jaw. 



III. The 875 millim. long female Orca fætus (fig. 3 in the letterpress p. 46) is of considerable interest. Its length 

 is nearly half that of the new-born animal, in other words nearly half-grown. The length of the head is a little less than ' .-, of that 

 of the trunk; on the mouth are 4 foetal hairs, the upper lip is of a sigmoid form, its hinder end stretching as far back as 

 beneath the anterior angle of the eye. The external nasal aperture is contained in a transverse plane passing through the 

 eye; the ear aperture is situated nearer the axil than the angle of the mouth. The pectoral fins, 120 millim. in length, 

 amount to about '/: of the length of the trunk, their breadth being about half their length. The trunk is relatively narrow, 

 with the greatest circumference between the pectorals and the dorsal tin. The umbilical cord is inserted a little in front 

 of the middle of the body, immediately under the front part of the dorsal fin. The dorsal fin amounts to Vis of the length 

 of the body, and has a convex anterior margin, the point being inclined backwards, and the posterior margin very concave: 

 the latter is continued in the shape of a low keel. The postanal segment is less than V» of the length of the body. The 

 210 millim. l)road tail fin (tig. 4 in the letterpress p. 47) amounts to rather more than '4 of the length of the trunk, this being 

 near by the same proportion that they bear to one another in the new-born animal {'/:, of the length of the trunk). There are 

 distinct dorsal and ventral keels. The hind margin is only slightly sigmoid; the cleft is relatively deep and the flukes rounded. 



The colouring of this embryo (fig. 3), is developed to such an extent that the type of the species cannot be 

 mistaken in lnoking away from the f(etal characters. The black line on the back on each side of the cervico-thoracic ])art 

 of the body is now less marked, and apparently ■ forms the boundary -line between the strongly-coloured mesial dorsal region 

 and the somewhat lighter sides. The foremost side-patch over the eye has a more indistinct posterior boundary, ('orapared 

 with the foregoing embryo, the pigmentation in the axil beneath the pectorals has advanced, and on the abdominal surface, 

 the boundary approaches the median line in such a way that the hinder white side-patch almost seems cut off in front, thus 

 giving this part, when viewed from the abdominal surface, the appearance of a three-lobed leaf with a narrow stalk in front. 



