150 _ 
absence of points on the ventral plates, is also not constant as 
will be seen from the last column, where it is again to be noted 
that the smallest form approaches nearest to the condition of 
Z. faber. 
One difference is found to be constant in all the species 
examined, namely, the position of the black spot on the side. 
In Z. faber it is in the middle of the body, about half way up the 
side and nearly equidistant from the posterior edge of the oper- 
culum and the lateral line, while in Z. capensis it is about $ up 
the side and just above or on the lateral line. 
On the whole the difference between the two species seem 
to be sufficiently well-marked to separate them as distinct 
varieties at least and the closer resemblance of the young forms 
of Z. capensis to the adult of Z. faber seems to indicate that the 
latter is the older form phylogenetically. This resemblance 
is in the presence of points on the ventral plates and forked or 
double spines on those at the base of the dorsal and anal. 
An examination of a considerable number (40) of small speci- 
mens, varying in total length from 18 to 50 mm., showed that 
this feature is constant in the young forms, the spines being as 
well developed in these as in the adults of Z. faber. They 
were procured as follows :— 

yl : 
| |__| Size, includ- 
Refer- | Locality. | No. | ing caudal, 
ence No. | in mm. |} 
15,390A. | Cape Point Lighthouse, N.E. by E., 6} miles .. I 17.1] 
10,315 Walker Point, E. by S., 5 miles .. a | Ig |  26—364 
10,417 Gericke Point, N. 57° E., 8 miles re! Hey yf etoy |) 36-49 
8,040 Cape Infanta, N.E. by N., 19 miles Ae ce | 43 1! 
2,880 Vondeling Island, N. + W., 9 miles I 22: | 
242A. | 23 miles S.W. from Cape St. Blaize.. 2 28-38 
10,423 Gericke Point, N.E.# E.,13} miles .. LO 23-50 

ET 
In all of these small specimens the large black spot was as 
in the adult, viz., on or above lateral line though in a few there 
were, in addition, less conspicuous spots elsewhere, usually 
alongside it, sometimes in the centre of the body, as in Z. faber. 
