Suborder 3. 



Platycopa. 



General Characters. Shell strongly calcareous, without any persistent 

 aperture in front, and in general appearance not very unlike that in some of the 

 Podocopa. Enclosed animal, however, built on a very different type. Both 

 pairs of antennae very powerfully developed and allowing to be extruded from 

 the shell in front, being however scarcely at all natatory, the anterior ones 

 multiarticulate and abruptly geniculate at the base, the posterior ones exhibit- 

 ing a structure totally different from that in any other known Ostracoda, being 

 broad and flattened, biramous, and in their general appearance somewhat re- 

 calling the legs of Copepoda. All the other appendages of rather weak structure 

 and wholly concealed within the shell. 3 pairs only of postoral limbs present, 

 none of them pediform; last pair in female quite rudimentary. Caudal rami 

 rather feeble, and differing conspicuously both in shape and armature from 

 those in the other known Ostracoda. No frontal tentacle present, nor any 

 distinctly developed visual organs or heart. 



Remarks. This suborder also was founded by the present author in the 

 year 1865 on a single genus, viz., Cytherella, the species of which at that 

 time were only known in a fossil condition, and which of course only could 

 be determined from the characters of the shell, the genus being considered as 

 nearly allied to Cythere. By the" discovery of a recent species occurring off 

 the Norwegian coast, I had an opportunity of examining also the enclosed body, 

 and found it to my great astonishment so totally different in structure from 

 that in any of the other Ostracoda known to me, that I could not hesitate in 

 establishing for the reception of this genus not only a particular family, 

 Cytherellidce, but even a distinct group of higher systematic rank, named as 

 above in allusion to the peculiar structure of the posterior antennae. The state- 

 ments about the remarkable structural details in this genus given by me at 

 that time, though unfortunately without any accompanying figures, have since 

 partly been confirmed by 2 other authors, Brady and G. W. Miiller, who has 

 given figures of the limbs in 2 nearly allied recent species. The latter author, 



