MVSIDACEA 



I 19 



(Fig. 79) described by Sars/ may be chosen as an example of 

 the Mysidacea. 



Tlie peculiarity of this form consists chiefly in the immense 

 elongation of the endopodites of the fifth, sixth, and seventh thoracic 

 appendages. Characteristic of the Mysidacea is the freedom of 

 the hinder thoracic segments from fusion with the carapace, otlier- 

 wise this animal is seen closely to resemble the Euphausia figured 

 (Fig. 102). Eucopia australis, like so many of the Mysidacea, is a 



Fig. 79. — EucojJia australis, young female, x 3. A, 1st auteima ; AbA, 1st 

 abdominal segment ; Ah.&, 6tli abdommal appendage; IC, eye ; T, telson ; TIi, 5tli 

 thoracic ajipendage. (After Sars.) 



deep-sea animal, being brought up witli the dredge from over 1000 

 fathoms ; it is very widely distrilnited over the Atlantic Ocean. 



Fam. 2. Lophogastridae. — The members of this family 

 {Lophogaster, GnatJwjjJunisia) agree with the Eucopiidae in the 

 possession of branched gills on some of the tlioracic 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 tlie thoracic limbs. The endopodites of the posterior thoracic 

 limljs 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 tlie brood-lamellae being developed only on 

 the more posterior pairs of thoracic limbs. A number of closely 



^ Challenger Ilcports vol. xiii. , ISSo. p. 55. 



