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by Gruvel ^ and in most regards this liolds good also for the male of Ibla Cuviingi. There 

 is however one detail which I found different from Darwin's description. Darwin speaks of an 

 imbedded portion of the peduncle of the little male jjassing obliquely through the chitine 

 membrane and corium lining the sack of the female, and running along amidst the underlying 

 muscles and inosculating fibrous tissue, attached to them by cement at the extremity. I have 

 always found the little male attached to the wall of the sack by means of a disc of cement, 

 but I could not observe that it passed through that wall. I think that the description given by 

 Gruvel, where he says (for Ibla qjiadrivalvis) that the mantle (Darwin's "sack") sometimes 

 forms a proliferation, through the centre of which passes the e.xtremity of the peduncle of the 

 male, explains what has been observed by Darwin. According to Gruvel the tubular part of 

 the male "s'enfonce dans le manteau de I'hote". This means, I think, that the mantle forms 

 an invagination to receive the extremity of the tubular part, not that this passes through it to 

 meet with the muscles of the female's or hermaphrodite's peduncle. 

 This species was collected at the following places : 



Stat. 51. April 19, 1899. Shore-exploration in Madura Bay and other localities in the southern 

 part of Molo Strait. A few small specimens attached to Pollicipes niitcUa. 



Stat. 86. June 18 — 19, 1S99. Reef-exploration Dongala, Palos Bay, Celebes. Specimens loose, 

 i. e. not attached to Pollicipes viitclla. (N.B. No specimens of Pollicipes were 

 collected at Station 86). 



2. Ibla sibogae n. sp. PI. I\', fig. 20 — 22. PI. V, fig. i — 8. 



female. Valves of a uniform dirty brown or red brown colour — no blue, neither 

 along the lateral margins nor on the upper interior surface. Spines on the peduncle without 

 blueish brown rings. Caudal appendages only .slightly longer than the pedicels of the sixth 

 cirrus; rami of the first cirrus unequal by 2 — 5 (as a rule 4) segments. 



Male. Closely resembling that of /. C2i7ni7igi Darwin. 



This species is unisexual like /. Ciiiiiingi Darwin, which it also resembles in many other 

 regards. The absence of the blue colour, together with a few slight differences I perceived in 

 the structure of the parts of the mouth, the cirri and caudal appendages, as also the circumstance 

 that /. Cimiingi lives attached to Pollicipes mitella as a rule, made it necessary to consider 

 the present form as a dift'erent species. Later investigation of a richer and if possible quite fresh 

 or living material of both forms may show however that they are not specifically different but 

 only represent two varieties of one species. 



F 



e m a 1 e 



The animals are somewhat variable in shape, that part of the peduncle to which the 

 capitulum is attached and which as a rule is considerably broader than the inferior part, sometimes 

 forming an abrupt swelling and sometimes quite insensibly sloping into the inferior part. In other 

 specimens there is a distinct constriction beneath the broader part, almost in the middle of the 



• Gruvel, A., Cirripedes des expeditions scientifiques du "Travailleur" et du "Talisman". Paris, igo2. 



48 



