REPORT ON THE TUNICATA. 
385 
Although Compound Ascidians are probably all hermaphrodite if the entire life of 
the Ascidiozooid be taken into- consideration, still it very often happens that particular 
Ascidiozooids when examined are found to have the reproductive organs of only one 
sex developed. This was the case in a number of the Challenger colonies, and in many 
of these cases I have been able to make out that the female organs develop first in the 
young Ascidiozooid, and then, after the ova have attained maturity and escaped, the 
male system begins to form, and is found in a fully developed condition in the adult 
Ascidiozooid only. I have found this protogynous arrangement in the following species, 
and it probably exists in many more : — 
Botryllida:. 
Botrylloides tyreum. 
Botrylloides fulgurale. 
Sarcohotrylloides ivyvillii. 
Polycyclus jeffreysi. 
Distomida:. 
Colella pedunculata. 
Colella thomsoni. 
Colella gaimardi. 
Colelki quoyi. 
Colella murrayi. 
Colella ramulosa. 
Tn a number of the Polyclinidte and Didemnidm also, only male reproductive organs 
were found in the Ascidiozooids examined, but in such cases it is not certain that the 
female system occurs only in the younger Ascidiozooids. 
In Ccelocormus huxleyi, on the other hand, a protandrous condition appears to exist 
(see p. 322), the male organs developing first, and being succeeded later on in the life of 
the Ascidiozooid by the female system. 
In some of the Polystyelidm the polycarps are unisexual, and the male and female 
polycarps differ in appearance. In one species, Goodsiria pedunculata, only female 
polycarps were found in the Ascidiozooids examined, but whether this is a case of 
protogyny or protandry is not known. Possibly it may be due to a unisexual con- 
dition of the Ascidiozooids. It would not be surprising to find that in a group where the 
polycarps have become differentiated and heteromorphic, one or more species were unisexual. 
Tailed larvae were found in a number of the colonies examined, either in the peri- 
branchial cavities of the Ascidiozooids or in a specially formed incubatory pouch (see 
Colella pedunculata, p. 89), or merely imbedded in the common test of the colony. 
The following list, giving the species in which larvae occurred, the dates when the 
(ZOOL. CHALL. EXP. — PART XXXVIII. 1886.) Pp 49 
