109 
outside the articulation of these appendages. The trunk is closely covered all over with 
the peculiar membranous hairs which are mentioned above as having been found on the anterior 
part of the trunk and on the genital area of the one specimen of S. elegantula. — Two still 
smaller specimens — the smaller one only 34 mm. long and ‘19 mm. broad, — are very like the 
last-mentioned specimen, which shows that these three very young animals differ very much 
from the older ones in the hair-covering of the head and — particularly — in that of the 
trunk. As a matter of course, the genital area is not developed in these small specimens, 
but the animal mentioned as measuring ‘41 mm. shows that, at least sometimes, this area 
does not develop its final shape till some time after the animal has lost the hair-covering 
that was characteristic of it when young. For want of ampler material I cannot decide 
whether this course of development is the rule in this species. 
MALE. A large specimen is ‘24 mm. in length. It is somewhat more clumsy than 
the male of S. elegantula, but on the whole closely resembles this species, as e. g. in the 
shape of the median frontal plate, which, however, is a little shorter, and in the legs, the 
long terminal setz of which are longer than each leg; but the anterior pair of trunk-legs 
seem to be smaller, compared with the basal joint of the maxillipeds, than in the afore- 
mentioned species; the caudal stylets are hardly so long. — The smallest male found is 
only -15 mm. long, but it seems to be just hatched, for the frontal plate is bent downward, 
the rostrum backward and the antennule turn backward (comp. p. 60). 
OVISACS. Are pretty large, but occasionally show great difference of size, being 
shortly oval or sub-globular. 
LARVA. A single hinged specimen was found, but is lost. 
POST-LARVAL DEVELOPMENT. Nine pupe have been found, all closely 
covered with hairs (fig. 4¢—4e); the smallest 115 mm., the largest -25 mm. in length. As 
for more particulars, I refer to the detailed account on p. 59—60. 
HABITAT. The marsupium of Corophium crassicorne Bruz. from Denmark. In 
one specimen were found one pupa and the smallest above-mentioned female; in another the 
smallest female but one and one male; in a third specimen a young female and a hinged 
larva; in a fourth the largest female but one, one male and four ovisacs of very different 
size; in a fifth specimen a small female; in a sixth animal the largest female, one pupa and 
two males, both fixed by a frontal thread, one of them being an adult, while the other was 
the above-mentioned, recently hatched individual. In a seventh specimen four ovisacs were 
found, no female, but the anterior halves of two males, which had evidently been destroyed 
before the host was caught. Finally, in an eighth specimen, two ovisacs and seven pupe, 
two of which were situated each on one side of the marsupial plate of the sixth (right) leg, 
one on the gill of the penultimate (left) leg, one on the inner side of the basal joint of the 
posterior left leg. 
