1974] 
Parsons Plewson Cryphocricos 
521 
verse section through a fringed seta near its base would appear as a 
nearly complete circle, with the open end facing away from the cuti- 
cle. Towards the tips the setae are wider, more flattened, and would 
appear as more widely open arcs in transverse section. Their outer 
surfaces bear longitudinal grooves corresponding to pronounced 
ridges on their inner surfaces. The apical portion of each of these 
ridges subdivides into several short projections which give the seta a 
fringed appearance. The sizes of the fringed setae vary considerably ; 
on the lateral edges of the ventral paratergites their length ranges 
from 12 to 38 fim, and their diameter from 6 to 15 ftm. 
Single fringed setae occur on nearly all parts of the ventral sur- 
face, but appear to be less common on the prothorax and the medial 
portions of the abdominal paratergites than on other regions. Large 
concentrations of them occur along the lateral edges of the third 
through eighth ventral paratergites. On the second paratergite the 
leaf-like setae extend all the way to the lateral edge, and there are 
few fringed setae. On the most posterior segments, however, the ex- 
treme lateral portions of the paratergites bear fringed rather than leaf- 
like setae. They occur in largest numbers on the edges of the fifth, 
sixth, and seventh abdominal segments and become increasingly less 
numerous on each of the more anterior ones. The eighth paratergite 
bears fewer of them than the seventh. 
In Cryphocricos hungerfordi a narrow strip bearing only plastral 
hairs separates the leaf-like and fringed setae, and the latter, which 
occur in a single row, are fewer and farther apart than in C. harozzii. 
The two types of setae are less clearly separated in C. harozzii, whose 
fringed setae are more numerous, closer together, and in several 
poorly-defined rows (Fig. 12). Their dense distribution on the lateral 
edges of the fifth through seventh paratergites in this species sug- 
gested, at first, that they might be hydrofuge devices. On the para- 
tergites of C. hungerfordi , however, they appear to be too far apart 
to function in this way. Their sporadic occurrence on nearly all the 
exposed surfaces of the body suggests that they have some other func- 
tion, probably a sensory one. 
Dorsal Surface 
The dorsal surface of the body was studied only briefly in one 
specimen of each species of Cryphocricos. In both specimens this 
surface is covered with considerably more silt and debris than the 
ventral one. The detritus clings to all the parts of the dorsum which 
are exposed to the water (Fig. 2, left side) ; these regions have a 
roughened appearance under the stereoscopic microscope. 
