272 
PACIFIC SCIENCE, Vol. XI, July, 1957 
INTERPRETATION OF ORAL AREA 
The highly modified and usually compact 
oral areas of poecilostome cyclopoids present 
particularly difficult problems in both the 
technical and graphical aspects of their study. 
Doubtless this has contributed to the differing 
interpretations of their anatomical features 
and the omission from many descriptions of 
all or part of the appendages. The viewpoint 
has already been expressed that "no species 
or genus should be proposed without tho- 
rough delineation of all the appendages” (M. 
S. Wilson and Illg, 1955). It is, of course, 
obvious that neither a taxonomy adequate for 
identification and differentiation of species, 
nor one that will contribute to classificatory 
knowledge, can result from neglect of some 
parts or mere cursory examination of others. 
The illustrations presented here for Tere- 
dicola typica are diagrammatic and their under- 
standing may be helped by further elucidation 
of some points. As noted in the description, 
the buccal mass is protuberant. It is supported 
anteriorly by the labrum and its framework 
and posteriorly by the maxillipeds and their 
framework (Fig. 19). An apparently newly 
molted specimen, relatively nonfleshy and 
with thin body membranes, was used for 
Figure 13. It is a camera lucida drawing from 
an in toto preparation, slightly flattened by 
cover glass pressure, and viewed ventrally 
with the compound microscope. Its illustra- 
tion cannot be other than diagrammatic, since 
the original is of necessity distorted, but such 
a view does establish the continuing relation- 
ship of the parts, which is impossible to show 
otherwise. 
The labrum is strongly united with the 
likewise laterally protuberant surface mem- 
branes, though a lightly sclerotized line ap- 
pears to define its actual lateral boundaries 
(shown by dashed lines in Fig. 13). The ven- 
tral posterior edge is free and protuberant. 
The mandible is entirely hidden in an in 
toto view, both because of its small size and 
its location below the labrum. It seems to be 
somewhat separated from the other appen- 
dages by a slight fold of the laterally protu- 
berant membrane. As verified from dissection, 
the base arises from a shallow framework of 
anastomosed, sclerotized strands, from which 
it was usually automatically separated during 
the manipulation of dissection. Because of the 
extreme reduction in size of the whole ap- 
pendage, the apical pieces of the right and 
left mandibles possibly may not meet one 
another in midline, but this was not exactly 
determined. They do, however, reach at least 
to the free posterior edge of the labrum, 
below which the oral opening is presumably 
situated. Figure 16 shows schematically the 
relationship of the mandible, maxilla, and 
paragnaths to the labrum. The exact place- 
ment of the appendages and other structures 
may perhaps be more easily determined from 
early copepodid stages in which the buccal 
mass is probably not so fleshy and protu- 
berant. 
In situ , the first maxi] la is elongate and 
appears to lie along the top of the inflated 
basal part of the second maxilla (Fig. 13). 
In actuality, its medial portion is slightly ex- 
panded dorso-ventrally, and lies close to the 
likewise expanded top portion of the second 
maxilla. In dissection, the two maxillae were 
frequently separated together, entirely free 
from the mandible. 
Since the relationship of the two anterior 
appendages in poecilostome cyclopoids has 
been much disputed in literature, some com- 
ments on their relationship and structure in 
Teredicola are appropriate here. The stemlike 
portion of the mandible appears to be at- 
tached to its skeletal framework near the apex 
of the first maxilla. When the whole buccal 
mass or separated anterior portions of it were 
observed and manipulated under the stereo- 
scopic microscope in lateral view and from 
above, it was clear that the mandible is more 
deeply embedded (that is, more dorsally situ- 
ated) than any part of the maxilla. This is a 
normal and expected condition when the pro- 
tuberant nature of the whole mass is con- 
