226 CEYLON PEARL OYSTER REPORT. 



abundance of Heterostegina depressa, which makes up as much as 40 per cent, of one 

 deposit, and often attains a size of 18*5 millims., and Amphistegina lessonii is not far 

 behind this in point of numbers. A considerable range of individual variation was 

 noticed, especially as regards the surface markings in such a case as Amphistegina 

 lessonii, and this has occasionally given rise to some difficulty in the determination 

 of species. 



The total number of species and varieties recorded is 131, belonging to 51 genera, 

 and of these 49 species are recorded for the first time from the seas around India 

 and Ceylon, most of the previous records being from the reports by Murray and 

 Chapman on the deposits obtained by H.M.S. "Investigator" in the Bay of Bengal 

 and the Arabian Sea. Only 15 species have actually been recorded previously from 

 Ceylon, consequently nearly all those mentioned in this report are additions to the 

 fauna of that colony. 



In conclusion, I have to thank Professor Herdman for the opportunity given me to 

 examine this interesting collection, and also for his very valuable advice throughout 

 the work. 



Note on a New Ramulina Deposit. 



Along the 100-fathom line, about 12 miles south of Galle, the dredge brought 

 up quantities of a remarkable and unique foraminiferal deposit, consisting of masses 

 varying in size from a hazel nut to a small apple 5 centims. in diameter, and formed 

 of many stout calcareous tubules. At first sight it would hardly oe taken to be of 

 Protozoan origin ; and, as a matter of fact, a few other animals occur with it. 

 Worm tubes extend into the ci'evices and wind about the tubules ; masses of 

 Polytrema and colonies of Polyzoa use the foraminifer as a support, and corals are 

 embedded by its vigorous growth. The result is a substantial marine deposit, which 

 cannot be of small importance in the building up of the ocean floor, and is still 

 another, and probably the most important case in the district, of the part played by 

 foraminifera in contributing to the form of the earth's surface, and in affecting the 

 metabolism of the ocean. This organism has been identified as a very luxuriant and 

 complex growth of a new species of Ramulina, which I desire to name after Professor 

 Herdman, by whom it was found and first identified as a Ramulina (see " Narrative," 

 this Report, Part I., 1903, p. 51). 



The genus Ramulina of Rupert Jones, 1875, is defined by Brady in the 

 ' " Challenger " Report ' as follows : " Test free, branching ; consisting of a calcareous 

 tube, swollen at intervals so as to form more or less definite, often irregular segments, 

 from which lateral stolons or branches are given off. Texture hyaline." Some 

 alteration will, however, have to be made in this definition of the genus, since this 

 new species is certainly not hyaline. The species described by Brady is It. globulifera, 

 and from the description it appears that the swellings referred to in the definition of 

 the genus arise only at intervals, and are connected by tubular portions. In our 



