. 
v MYSIDACEA UO) 
(Fig. 79) described by Sars,’ may be chosen as an example of 
the Mysidacea. 
The pecuharity of this form consists chiefly in the immense 
elongation of the endopodites of the fifth, sixth, and seventh thoracie 
appendages. Characteristic of the Mysidacea is the freedom of 
the hinder thoracic segments from fusion with the carapace, other- 
wise this animal is seen closely to resemble the Huphausia figured 
(Fig. 102). Hucopia australis, like so many of the Mysidacea, is a 
Fig. 79.—Hucopia australis, young female, x 3. A, Ist antenna; Ad.1, Ist 
abdominal segment ; Ab.6, 6th abdominal appendage; /7, eye; 7, telson; Th, 5th 
thoracic appendage. (After Sars.) 
deep-sea animal, being brought up with the dredge from over 1000 
fathoms; it is very widely distributed over the Atlantic Ocean. 
Fam. 2. Lophogastridae. — The members of this family 
(Lophogaster, Gnathophausia) agree with the Kucopidae in the 
possession of branched gills on some of the thoracic limbs, in the 
absence of auditory sacs on the sixth pair of pleopods, in the 
presence of normally developed pleopods in both the male and 
female, and in the brood-lamellae being developed on all seven 
of the thoracic hmbs. The endopodites of the posterior thoracic 
limbs are, however, of a normal size. 
Fam. 3. Mysidae.—These differ from both the foregoing 
families in the absence of gills, in the presence of an auditory 
sac on the sixth pleopods, in the reduction of the other pleopods 
in the female, and in the brood-lamellae being developed only on 
the more posterior pairs of thoracic limbs. A number of closely 
1 Challenger Reports, vol. xiii., 1885, p. 55. 
