Ze LEONARD DONCASTER. 
8. Sagitta robusta nov. sp. (Plate XIII, figs. 1A, 1B.) 
This species is abundant in the material collected in winter, but scarce in that obtained 
in April. It is characterized by the great thickness of the body-wall, especially of the 
longitudinal muscles. 
The length of mature specimens is 16 cm. of which the tail segment makes up one- 
fourth. The head is broad; the anterior fin is as long as the posterior, but narrower, its 
front end is opposite the posterior end of the abdominal ganglion. Both posterior 
lateral fins and tail fin reach the vesiculae seminales. The fin-rays do not extend quite 
to the base of the fins. The epidermis is thickened behind the head. The corona 
ciliata is long and narrow, beginning in front of the eyes just behind the brain, and is in 
shape an elongated ellipse, without the cross-shape found in S. bipunctata. There is a pair 
of diverticula at the beginning of the intestine, like those in S. minima. The ovaries are 
extremely long, and extend in fully mature specimens to the anterior transverse septum, so 
that the coelom of the trunk becomes almost obliterated. The vesiculae seminales project 
somewhat. Hooks usually 8, with very small points; anterior teeth 9, posterior 10—14. 
I have found this species also among Chaetognatha collected at Singapore. 
9. Sagitta ferox nov. sp. (Plate XIII, fig. 2.) 
A species closely resembling S. robusta, but distinguished by several constant differences. 
It is less abundant than the latter, and did not occur in the April collection. 
The body-wall is very thick, with powerful muscles. The tail segment is rather more than 
one-fourth of the whole length, which is about 1°2cm. The fins are almost as in S, robusta, 
but the posterior does not quite reach the vesiculae seminales, which project only slightly. 
The epidermis is slightly thickened behind the head. There are intestinal diverticula as in 
S. robusta, and the ovaries are extremely long, as in the latter, but they do not quite reach 
the front end of the trunk-cavity. Hooks 5, or sometimes 6, very thick and powerful, with 
rather blunt points; anterior teeth about 6, posterior 10, with blunt points and rather broad. 
As will be seen from the above description, this species differs very slightly from the 
last, and should possibly be classed with ‘it. In some points, however, there is a constant 
difference. There are never more than 6 hooks in S. ferow, and there are usually only 5, 
while in S. robusta there are 7 or 8, and the hooks of ferow are thicker and have larger 
point-pieces than in the other species. The teeth of ferow are also thicker and rather fewer 
in number. In no specimen was the corona ciliata found complete in ferow, but from the 
traces that remain it seems to resemble that of robusta. When preserved in formalin ferow 
always has a faint pink colour, while robusta is white or yellow, and is rather less opaque. 
10. Sagitta gardineri nov. sp. (Plate XIII, figs. 5A, 5 B.) 
A moderately abundant species in the winter collection, 
Length 25cm. Body thick and transparent, resembling that of S. magna. Head broad 
and short. Tail segment one-fifth of length of whole. Fins like those of S. magna; the 
rays do not quite reach the base. Ovaries when mature rather long, extending to the 
posterior end of the anterior fin; they are thicker and shorter than in S. magna, but 
proportionately longer than in S,. enflata. Vesiculae seminales spherical, placed at the front 
