NO. 8567 LABIDOCERA JOLLAEK GROUP—FLEMINGER 4] 
slightly larger in males (ca. 0.04 mm) despite the larger TL in females. 
On the other hand, the prosome is about 0.5 mm smaller in the male. 
TL-PUR relationships in diandra are surprisingly different from 
those in jollae and kolpos. Males and females not only fail to differ 
appreciably, but have essentially the same ranges, means and medians. 
There are other notable differences as well. Both sexes of diandra 
tend to be considerably larger than their counterparts in jollae and 
kolpos. In the male sex there is virtually no overlap in TL range 
between diandra and the other two species (fig. 16). In the female 
sex the smallest sized diandra occur near the middle of the range for 
jollae and kolpos. On the other hand, the entire distribution of PUR 
in diandra falls midway between the gap separating the two sexes 
in jollae and kolpos. 
In other words, these data show that for each species of the jollae 
group, males and females either barely overlap or completely overlap 
in the distribution of TL and PUR; furthermore, the geographical 
arrangement is such that only unlike pairs of species have a measure 
of geographical contact—that is, the pair of species with the same TL 
and PUR characteristics, jollae and kolpos, are geographically iso- 
lated from one another. In contrast, diandra, bordering on the 
geographical range of each of the other two, differs not only in the 
distribution of TL and PUR ranges, but also in having males and 
females sharing the same values. 
Bayly (1962, table 9) working with a fresh water calanoid, Boeckella 
propimqua, presents evidence that the proportional relationship of 
female length to male length remains fairly constant despite seasonal 
changes in absolute length of adults. Using his values, the ratio 
9 x length/ x length in B. propinqua varies from 1.09 to 1.24 with 
a median of 1.12. He later (1964) expressed the opinion that this 
ratio tends to vary significantly among different species of Boeckella. 
The significance of sexual and interspecific differences in TL and 
PUR should become more apparent after more is known about the 
behavior of species in the jollae group; however, the probability that 
they came about by chance alone seems most unlikely. For one thing, 
if mating is instinctive and ritualistic as previously discussed (pp. 27— 
29), the range limits of certain body proportions should prove to be 
critical. Successful mating requires the male to eject, position, and 
cement a complicated coupling device about one-third of TL while 
limited in movement because it must hold the female with its clasping 
appendages and maintain a position from which accurate sperma- 
tophore placement is feasible. On the basis of the differences in TL 
and PUR shown above, one or more details of copulatory behavior 
of diandra may differ appreciably from that of jollae or kolpos. On 
the other hand, there is no reason to anticipate such a difference 
