28 



orifice is a fissure ol' the usual anteriorly concave form with raised edges, of which the front one is the higher. The 

 transverse plane through the blow-holes passes through the eye region a little in front of the anterior angle. 



The shape of the trunk is elegant on the whole, and not clumsy. The contour of the back from the crown of 

 the head sinks slightly in the region above the pectorals. The greatest circumference is between the pectorals and the navel, 

 beyond which the body gradually tapers at the sides. The pectoral fins are situated, as in L. acutus, rather far down 

 towards the ventral surface. They are rather broad, and not nearly so pointed as in D. acutus, a fact which Liitken (116) 

 also remarks. The superior dorsal margin forms an obtuse-angled convexity, which passes into a distal concave portion. The 

 insertion of the umbilical cord is rather more in front of the middle of the body, being farther forward than the dorsal 

 fin. From the uavel to the genitalia externa (vulva) there is a groove in the hinder part. The clitoris and preputium lie 

 on the same level as the labia majora. The mammæ pudendales form two small prominences with a fissure in which lies 

 the papilla. The greater part of the dorsal fin lies beyond the middle of the body (posteriorly). As in the full-grown 

 animal, it has a long, backward-bending point. Its basal portion extends Ijackwards for some distance as a keel. The 

 post-anal segment amounts to rather less than Vs of the length of the body, and appears most compressed just in front of 

 the tail-fin, as in the full-grown animal. A considerable dorsal and ventral keel is developed, which is most elevated midway 

 between the anus and the cleft of the tail-fin, disappearing on the tail-fin itself The latter is deeply cleft, in the shape 

 characteristic of the species. 



The distribution of colour in this embryo, as in corresponding embryos of L. acutus, is already so 

 strongly marked, that several of the specific characters disclose themselves. The bluish grey colour, often tinged with brown, 

 extends from the facial part immediately above the "beak", backwards over the head and back, spreading over the greater 

 part of the post-anal part of the body. On the head, the dark skin colour extends below the eye, its boundary being an 

 obliijue line from the angle of the mouth downwards and backwards to the shoulder-joint. The pectorals are wholly dark, as 

 in L. acutus. The eye region is somewhat lighter, while a darker band runs from the "beak-furrow" to the eye region, 

 where it becomes paler. On the sides of the liody, between the pectorals and the genital region, the colour is a 

 lighter, yellowish grey. There is also a rather lighter shade of colouring over the dorsal part of the post-anal section of 

 the body, as also over the back of the head and neck on each side of the median line, from the neighbourhood of the 

 blow-holes backwards to about midway between them and the dorsal fin. The lighter, unpigmented part includes the "beak'", 

 the lower jaw, and the whole of the chest and ventral surface to beyond the anus, whence it extends like a light Ijorder 

 along the ventral keel, to the inferior surface of the tail-fin. 



The somewhat larger 7 60 mil lim. long fietus agrees in every respect with the above. It had 4 fcetal hairs on 

 each side of the upper jaw. 



II. The full-grown fætus (male, 1130 millim. long) presents no striking differences from the embryo just 

 described, except that the characters have gained a still greater similarity to those of the more full-grown specimen. The 

 length of the head is contained from 47= to 5 times in that of the body, the pectorals amount to Vsy, of the total length, 

 the insertion of the navel string is considerably in front of the middle of the body, while the dorsal fin is rather behind than 

 exactly over the middle (in the full-grown animal it is more in front of the middle). 



The "beak" in this specimen, besides being bounded at the sides by a deep furrow (the beak-furrow, sulcus 

 rostralis) is also separated in front on the median line from the pre-nasal facial part lying above it. The relative position 

 of the nasal aperture is about the same as before described. The eye region is less prominent, and the minute ear 

 aperture appears as a white spot of the size of a pin's head. The distal end of the broad pectoral is more rounded, 

 and upon the concavo-convex dorsal margin, the convexity includes the proximal half (in D. acutus the proximal V*)- The 

 penis is about to be drawn into the fold of skin, and is already partly hidden. Immediately in front of the anus lie the 

 two small folds which indicate the rudimentary mammæ masculinæ; but they lie nearer to the anus than is the case in 

 D. acutus. The post-anal segment, which is less than 'A of the total length, has, in its middle, vertical portion a high 

 dorsal and ventral keel. This part of the body is 14 centim. high. 



Several teeth are visible in the cavity of the mouth, coming through on the side portions of the jaws, while in 

 front there is no trace of them. The teeth feel soft to the touch. The tongue is free in front, and fringed at the edges. 

 On each side of the upper lip were found 4 ftetal hairs (cf. James Grieg 117, p. 16). Liitken found on the largest of the embryos 

 described by him, 3 hairs on the one side and 4 on the other, while the smallest had h on each side. Cunningham and 

 Clarke have, as is well known, recorded 4 bristles on each side of the upper lip of the young "White-beaks". Grieg found 

 bi'istles on a male 2.0.5 metres in length. 



