When the larva has found its new host, it attaches itself either beneath the cara- 
pace to the branchiz or in the marsupium to one of its plates, to one of the gills, or simply 
to the ventral surface of the body, or to the basal part of a leg, and in case it attaches 
itself to a not full-grown female of Amphipoda, of course it must content itself with one of 
the three last-mentioned places. The larve of Aspidoecia fasten themselves either outside 
on the dorsal surface of the host (an Mrythrops), if they are growing into females, or on 
a female of their own species (pl. XII, fig. 3b), if they are going to be males. The fixation, 
which is very solid, is effected by a viscous substance, which expands itself so as to form a 
larger or smaller plate on the front (pl. IV, fig. 1e,s; pl. VIII, fig. 2i; pl. XI, fig. 1e,s). 
This viscous substance must be secreted of a gland in the front part of the head, the orifice 
of which, however, I have tried in vain to find; the gland itself must be studied from fresh 
material. (It was pointed out long ago by several authors, that the larve of various Caligide, 
of Achtheres etc., in their first stage fasten themselves in a somewhat similar manner by a 
»Stirnband« (Claus).) The larva, after hinging itself in this way. relaxes the grip of its 
limbs and hangs quite free; thereupon it begins to change form, bending forward the last 
joint of the maxillz, and its cephalothorax getting gradually shorter and broader (pl. XT, 
fig. Le; pl. LV, fig. le); how short and broad it may occasionally become, may be seen on 
pl. [V, by comparing fig. 1c, which represents a free larva, and fig. 1d, which represents 
a larva that has reached its full breadth, and which no doubt is going to develop into a 
male; fig. le is an intermediate form shortly after the fixation. Then the muscles etc. in 
all the limbs and in the abdomen dissolve themselves, and the contents of these organs are 
transferred into the cephalothorax, the muscles of which have also been dissolved, and finally 
this united substance is surrounded by a new skin under the old one. The subsequent 
development will be treated in the next division. 
e. The post-larval Development; the Pupe. 
The post-larval development, which takes place between the larval stage just described 
and the appearance of adult males and of females (which, though very small, in all important 
features resemble the egg-laying specimens), offer the greatest deviations between the different 
forms, but, unfortunately, the representation I am capable of giving is very fragmentary. 
The larva in many cases develops into a pupa, out of which evolves the female, and, in 
some cases, the male; in other cases the male is developed immediately from the larva etc., 
and in Mysidion the metamorphosis is more complicated. I know the complete development 
only of two species of Spheronella and of Homocoscelis minuta, but the two first-mentioned, 
in particular, are fortunately very different from one another; I know, moreover, the develop- 
ment of the male in Aspidoecia, and of the females belonging to the species of the Spher. 
Leuckartii-group. Finally I have found a pupa of each of four other species of Spheronella 
