141 
of mouth 3:1, and length of pectoral 1:2, in the length of the head 
eye, 2°5 in the interorbital space. 
Head depressed before, raised behind. Snout pointed in profile. 
Nostrils large, wholly below and not approaching the lateral margins, 
much nearer the mouth than the tip of the snout. Mouth small, 
obtusely angular; a long fold at the corner of the upper, and a short 
one on the lower, ip. Teeth small, smooth, arranged pavement-like 
in about thirty very oblique rows. Spiracle longitudinally oval, half 
the length of the pupil, its own length behind the eye. Nictitating 
membrane merely an extension of the lower eyelid, with scarcely 
trace of fold when drawn. The two posterior gill-openings above 
base of pectoral, the last one small. 
Body compressed ; a prominent ridge runs from the occiput to 
the upper base of the tail, and another along each side of the body. 
Shagreen very fine. 
Fins.—First dorsal a little nearer the insertion of pectoral than to 
the ventral. Second dorsal smaller, its origin nearer caudal than 
hinder insertion of the first dorsal. Anal small, its origin beneath the 
middle of the base of the second dorsal and midway between the 
hinder insertion of the ventral and the caudal. Pectorals a little 
larger than the first dorsal; imsertion of ventral nearer anal than 
pectorals. The length of the caudal equals the space between the 
two dorsals, and the length of its peduncle is 1°8 in its own 
length. 
Colour, greyish blue above and white beneath; the coloured 
portion above with numerous very small white dots, which are close 
together, and evenly disposed along the lateral ridge. 
Length of specimen described, 475 mm. (= 18? in.). 
The smooth-hound is the smallest but at the same time by far 
the most numerous shark on the coast. It was taken, with but few 
exceptions, at all stations, and at depths ranging from 10 to 
105 fathoms. It was not obtained at the Chatham Islands. — 
M. antarcticus agrees with the European M. levis in having the 
embryo attached to the uterus by a placenta, a fact first noticed and 
described by Parker.* We obtained many young ones from the 
females, the largest number counted being eleven, six in one and five 
in the other uterus; they are similar to those previously described 
and figured by me. It may be noted that the peculiar form of the 
yolk-sac is retained until its complete absorption. In examples just 
prior to birth, the sac is like a small bean, the cord still entering 
towards one end. 
In colour and general form the embryos bear some resemblance to 
those of Galeus, but may be at once distinguished by the smaller 
mouth, the position of the nostrils (removed from the margin of the 
head), the large second dorsal fin, and the simpler form of caudal. 
* Parker, Trans. N.Z. Inst., xv, 1883, p. 219. 
