284 THE SCHIZOPODA. 
which, for the others, must always be very difficult, as frequently it will be next 
to impossible to find specific characters for every stage of every species. As the 
number of species of the genus Euphausia collected by the Agassiz expedition 
1904-1905 is fourteen, and it may be expected that larvae of the majority of these 
species exist in the material, it will instantly be seen that to solve the difficulties 
connected with the endeavour to refer the older larval stages to their proper 
form and then in a similar way to proceed from older to younger stages would 
have been in most cases at least very great and sometimes or frequently impos- 
sible. Under such circumstances I thought it better not to make a hazardous 
attempt to work out the material of these larvae, with the exception of some few 
presenting a somewhat peculiar aspect and belonging to a single species. But 
I thought it useful and safer to describe a number of larvae of five other genera, 
hoping thereby to give an addition of some little importance to our knowledge 
of the larvae of this order, especially as I am able to refer most of these larvae 
to the species in question. 
THYSANOPODA sp. (T. MoNACANTHA aff.). 
Plate 12, figs. la—lg. 
A. First Furcilia-Stage (figs. la-1d).— The frontal plate (fig. 1b) very 
long, nearly as long as broad at the base; its lateral margins proximally concave, 
more distally convex and then almost straight to the slightly acuminate, acute 
tip; the upper surface a little concave longitudinally.— The carapace ‘thas a 
fine denticle on the lower margin somewhat before its posterior end (fig. la); 
seen from the side a short, but somewhat high keel, including the dorsal organ, is 
seen on the upper margin considerably nearer to the posterior margin than to 
base of the frontal plate.— The eyes are large, yellow with the central part black, 
but they do not reach beyond the sides of the carapace (fig. 1b), as their stalks 
are short.— The antennular peduncles short and very robust; first joint ex- 
tremely broad, with its distal outer process reaching the end of third joint and 
furnished with fine spines on the inner margin; second joint broader than long 
with two very long, plumose setae on the inner margin; third joint nearly half 
as long again as the second and a little longer than broad, with terminal setae 
and three very long, plumose setae on the inner margin; both flagella are one- 
jointed, the upper much shorter and thinner than the lower which is a little 
shorter than the third peduncular joint.— The antennae (figs. la and 1b) with 
both rami one-jointed and terminating in a bundle of extremely long, plumose | 
