44 



The pectoral fins, 59 millim. long, are situated at the transition from the first to the second quarter of the 

 trunk. They amount to nearly '/t of the length of the trunk (in the older male, between Vs and Vs, in the older female, 

 Vs. according to Lilljeborg; in the new-born female which will be described subsequently, the length of the pectorals is V» oi 

 that of the trunk). As before stated, the pectorals have already assumed the typical Orca shape; they are blunt, rounded 

 and foliate: their greatest breadth is equal to nearly half their length. 



The trunk is of a distinct spindle shape with its greatest thickness near the pectorals. The umbilical cord is 

 attached in front of the middle of the body, and immediately beneath the foremost ascending margin of the dorsal fin. The 

 post-anal segment is somewhat less than V:t of the length of the body, and is characterised by distinct dorsal and ventral 

 keels. — The dorsal fin is situated in the middle of the dorsal surface of the body; it is 26 millim. in height, with a 

 slightly convex, retreating front margin, and a slightly concave hind margin descending almost vertically. The width of the 

 dorsal fin at the base amounts to nearly I'/a times its height, and the hind margin is continued in the dorsal keel. — The 

 tail fin is 8.5 millim. broad and V*.» of the length of the trunk, that is to say of about the same proportion as in the 

 full-grown animal. It is triangular in form, with a small cleft and a very slightly sigmoid hind margin. 



The colouring on this embryo, which further demonstrates the Orca type, is of special interest (PI. V, fig. 1). 



The typical "neck-band'", appearing in the Lagenorhynchus embryos, also appears in the Orca, though somewhat 

 indistinct in so slightly developed a fætus as the one under consideration. A dark band may be noticed in front of the 

 eyes, stretching backwards and upwards over the most convex part of the head. It describes a semicircle open to the front, 

 and at the back of the head and neck exhibits a proportionately darker colour than the less strongly coloured surrounding 

 parts. On the liead. the colour boundary shows conditions almost similar to those in the fully-developed animal, except that 

 the colours are naturally not so dark. For instance, the region round the nasal aperture has still but Httle colour. The 

 eye region is surrounded at the back by a darker ring (fig. 1) and the eyelids have begun to be coloured, while the intermediate 

 part is still rather light. 



The colouring upon the trunk already exhibits, on the whole, the typical distribution peculiar to the Orca, l)ut the 

 boundaries are more indefinite, and in the caudal segment the pigmentation is' very little developed. The pectorals are of 

 a blackish grey with the characteristic anterior transverse border. On the sides of the body behind the pectorals, the dark 

 colour extends far down over the surface of the abdomen, into the region round the navel, while somewhat behind it, extending 

 round the anus, is seen on each side the oval patch of white (fig. 1) typical of the Orca gladiator (fig. 2). The dorsal fin 

 is almost black on its anterior convex border, but is lighter behind. Below and near the posterior margin of the dorsal fin 

 an irregular, lighter patch is observable, which indicates the spot where, in many full-grown specimens, a purple patch is 

 found. — At the junction of the back with the sides, a blue-black line is found on each side running from the region behind 

 the dorsal fin almost to the eye; it has a slightly sigmoid curvature, and stands clearly out on the blue-grey ground. This 

 narrow, strongly-coloured band, which begins above the foremost white patch by the eye, expands into the shape of a fan 

 immediately behind the dorsal fin, and below the light part which is purple in the full-grown animal. 



The white colour (i. e. the unpigmented part) is thus distributed over the whole of the lower jaw, the extreme 

 edges of the upper jaw, and the lower part of the head as far as the pectorals, where the line of demarcation runs almost 

 vertically down to the axil. An oval white patch lies behind the eye. The surface of the abdomen is white between the 

 pectorals, but behind them there is only a narrow white band along the median line until a little beyond the navel. Here, 

 liowever, the white colour spreads out to each side to form the characteristic large, elongated oval patch of white on each 

 side of the pudendal and anal region. The greater part of the ventral keel and of the inferior surface of the tail fin is also white. 



In comparing this fcetus with the previously described Lagenorhynchus acutus fætuses, we find that it ought 

 properly to be classed with those of about 20 centim. in length, where the length amounts to about \/3 of that of the new-born 

 animal. The distribution of colour, however, in the above described Orca fætus shows greater developement and is more 

 cliaracteristic than in the corresponding Lagenorhynchus fietuses. 



A considerable portion of the fætal membranes was adhering to this fætus ; it will be described in a subsequent chapter. 



le 



II. The 015 millim. long fætus mase, exhibits in certain of the circumstances of its external form, and in tl 

 distribution of cdlour, a further developement of the characters enumerated in the description of the 40.8 centim. long fætus. 

 The head curve is very slight. The length of the head is contained 4V2 times in that of the body ; the navel lies a little 

 in front of the middle of the abdominal surface. The front part of the dorsal fin is vertically over the navel. The distance 

 from the anus to the tail cleft — the post-anal segment — amounts to rather less than 'Ai of the length of the body. The 

 ])ectorals are situated at the beginning of the second quarter of the body, reckoning from front to back. 



In fd'tuses of the size here described, the head has a more pointed snout. Seven fætal hairs may now be 

 counted on each side of the upper jaw; they form a curve with the convexity downwards. The edge of the upper lip describes 



