CIREIPEDIA. 147 



calcareous substance without immediate danger to itself, is scattered all over the 

 pieces of Turbinaria examined, the other forms occurring with it are almost entirely 

 confined to the inner parts of the colony (where growth is less vigorous, the maximum 

 thickness having been almost reached), or to parts where the living tissues have been 

 killed or weakened by boring organisms. 



*Balanus tintinnabulum (L.). 



Locality : Cheval Paar, Gulf of Manaar. 



The only specimen which T can refer with certainty to this extremely variable 

 species belongs to the variety communis, which I have taken also on the Pamban 

 Channel, between the Gulf of Manaar and Palk Bay. The shell of Professor 

 Herdman's specimen is partly covered by an incrusting Alcyonarian. 



*Balanus amphitrite, Darwin. 



Localities : Galle ; Gulf of Manaar. 



Numerous specimens on shells, ropes, and submerged baskets. All but one belong 

 to the variety venustus, which I have taken on an Avicula attached Co a Gorgoniid 

 at Kilakarai, on the Indian shore of the Gulf of Manaar. The one exception 

 represents the variety comnnmis. Both these varieties have an extremely wide 

 distribution, and Professor Herdman's specimens are quite typical. 



The most interesting are those on the submerged baskets, as their approximate 

 age is known. The baskets were put into the sea on April 17 and were drawn out 

 on May 9. The Barnacles which had formed on them during this period measure 

 from 3 millims. to 8 millims. in their antero-posterior diameter, while the largest 

 individuals obtained from the same seas measure about 14 millims. It is clear, 

 therefore, that individuals of this species take, at this season, not more than three 

 weeks to attain more than half their adult size. I have recently recorded a case in 

 which a specimen of B. tintinnabulum (12) was known to have reached a great size 

 (diameter of base, which was approximately circular, 60 millims ; height of shell, 

 <l. r > miHims. ) in about a year at Pamban, on Rameswaram Island. 



Professor Herdman tells me that B. amphitrite and possibly other species grow on 

 the shells of living pearl oysters in the Gidf of Manaar. They appear in April or 

 May, and spread with great rapidity. Such forms may be classed as enemies of the 

 pearl oyster. 



*Balanus amaryllis, Darwin. 



Localities: Palk Bay and Gulf of Manaar. 



The majority of these specimens belong to Darwin's variety B, but a few are 

 obscurely striped with dull pink. The opercular plates resemble those of the typical 

 form, rather than of that noted by Weetner (5), and later described by Lanchester (8) 

 as suh-species dissimilis. The specimens are all small. 



U 2 



