Spermatophore of Dardanus asper — Matthews 
265 
TABLE 1 
The Presence, Absence, or Modification in Other Species of Crabs of the 
Nine Regions of the Vas Deferens Proposed for D. pugilator 
SPECIES 
region 
Diogenes pugilator. 
1 
2 
3 
4 
5 
6 
7 
8 
9 
Eupagurus hernhardus 
p 
P 
P 
a 
P 
a 
P 
P 
P 
Eupagurus prideauxi. 
P 
P 
P 
a 
P 
a 
P 
P 
P 
Eupagurus cuanensis 
P 
P 
P 
a 
P 
a 
P 
P 
P 
Anapagurus hyndmanni (left side) 
P 
P 
P 
a 
P 
a 
P 
P 
a 
Anapagurus hyndmanni (right side) 
P 
P 
P 
a 
P 
a 
P 
P 
P 
Clihanarius misanthropus 
P 
P 
P 
a 
P 
a 
a 
a 
P 
Pagurus arrosor. 
P 
m 
m 
m 
m 
a 
a 
a 
P 
Dardanus asper. • 
P 
m 
P 
P 
P 
P 
a 
m 
P 
p ~ presence; a ~ absence; m = modified. 
pedestal is produced in the form of a con- 
tinuous ribbon which upholds the individual- 
ized stalks. 
6. In the thick part of the spindle the stalks 
are stretched. 
7. At the distal extremity of the spindle, 
the segmentation of the ribbon of the pedestal 
takes place. 
8. In the tube which comes after the spin- 
dle, the spermatophores are in single file in 
the canal, the ampullae directed proximally. 
9. The canal becomes larger, the ampullae 
dispose themselves in any way, the pedestals 
staying in rank, one after another, until they 
reach the genital aperture. At the beginning 
of this region the gland cells secrete a mucus 
which surrounds the spermatophores. 
The presence, absence, or modifications of 
these nine regions in the species so far ade- 
quately investigated are summarized in Table 
1. Dardanus asper, although possessing region 
1, does not possess a well-defined region 2 
in which the coils of a right-handed helix 
secrete the sperm-column sheath. In this re- 
spect the vas deferens of D. asper resembles 
Pagurus arrosor in which a fine tube of con- 
secutive, closed turns rotates now to the right 
and now to the left. D. asper resembles Eupa- 
gurus hernhardus, E. prideauxi, E. cuanensis, 
Anapagurus hyndmanni, Clihanarius misan- 
thropus, and Diogenes pugilator in that the 
sperm column is segmented between regions 
2 arid 3. Dardanus asper resembles Diogenes 
pugilator in possessing region 4, where the 
stalks appear, region 5, where the pedestal 
is developed, and region 6, in which the stalks 
are lengthened, but differs from Diogenes pugi- 
lator, E. hernhardus, £. prideauxi, E. cuanensis, 
and A. hyndmanni in not having region 7, 
where the pedestal is segmented. Although 
D. asper possesses region 8, in which the 
spermatophores are in single file, the ampullae 
are not necessarily directed toward the begin- 
ing. 
In so far as can be determined, D. asper 
is the only hermit crab which has been in- 
vestigated in which the stalks lengthen, but 
the pedestal fails to segment. The sperma- 
tophore of D. asper may appear sufficiently 
different from those previously described for 
other hermit crabs to set it apart in the scheme 
of spermatophoric development. However, 
too few genera have been investigated to draw 
any valid comparisons either on the com- 
plexity of their vasa deferentia or the sperma- 
tophores which they produce. In all hermit 
crabs studied the spermatophore is developed 
with great precision. It is always possible to 
determine the species by careful examination 
of the spermatophore. The effects of a chang- 
ing environment on the form of the sperma- 
tophore should prove in Coenohita and Birgus 
a lucrative field for further investigations. 
RESUME 
The effect of crowding on the reproductive 
