A Visit to Damma Island. 49 



cells," which result from the amoeboid degeneration of the 

 collared cells. These he traces to the ectoderm, and lie 

 suggests that they are excretory in function. 



Secondly, he finds that the ectodermal gland-cells (for 

 which he claims a general occurrence in sponges) are excre- 

 tory in function, and conduct a process of intracellular 

 excretion. I can find, however, no evidence in his paper of 

 the occurrence of diapedic nephi'ocytes, which are so clear a 

 feature in the form I studied, unless, indeed, his Metschnikoff 

 cells be shown later to leave the colony through the ectoderm. 



The course of the metabolic circuit tlirough the tissues, 

 including the identification of the endodermal choanocytes 

 and the so-called " mesoderm," both morphologically and 

 physiologically, and the part played by each in ingestion and 

 digestion, are all points in which Mr. Bidder's conclusions, 

 arrived at independently and prior to my own, agree with the 

 latter, and confirm the doubts which I expressed with regard 

 to Lendenfeld's deductions. 



The importance of the collar-cell metamorphosis from a 

 phylogenetic point of viewmay be expressed in the statement 

 that further proof tlian at present exists must be forthcoming 

 before the presence of a true mesoderm or middle germinal 

 layer in the sponges can be accepted as an established fact. 



XIII. — A Visit to Damma Island, East Indian Archipelago. 

 By James Walker. — With Notes on the Fauna^ by R. B. 

 Sharpe, G. a. Boulenger, E. A. Smith, R. I. Pocock, 

 C. O. Waterhouse, C. G. Gahan, W. F. Kirby, and 

 F. A. Heron. 



The volcanic island of Damma, one of the northernmost out- 

 liers of the Serwatty Group, is situated almost exactly halfway 

 between the large islands of Timor and Timor- Laut, and about 

 350 miles from the nearest point of the coast of Australia. 

 It is less than ten miles in length by about five miles wide, 

 and thus ranks among the smaller members of the great 

 Eastern Archipelago, while it is certainly one of the most 

 remote and least known of them all. Though the island has 

 been for some time in the possession of the Dutch, nothing 

 was known of its natural history previous to the visit of 

 H.M. surveying-ship ' Penguin,' so far as I can ascertain, 

 except that a Dutch collector had landed there for a short 

 time and had procured a few birds. It was the cause of no 

 little satisfaction, both to myself and to my energetic fellow- 

 worker, Dr. P. W. Bassett- Smith, that orders were received 

 Ann. & Mag. K Hist. Ser. 6. Vol. xiv. 4 



