PEOP. A. DENDT ON PONTOBOLBOS. 443 



On Pontolollos, a Eemarkable Marine Organism from the Gulf 

 of Manaar. By Aethub, Dendt, D.Sc, F.L.S., Professor 

 of Biology in the Canterbmy College, University of New- 

 Zealand. 



[Read 18th November, 1897.] 

 (Plates 26 & 27.) 



Some years ago I received from Mr. Edgar Thurston, Super- 

 intendent of the Grovernment Central Museum at Madras, a 

 number of Sponges collected in shallow water off the shores of 

 Eamesvaram Island, i. e. the Madras coast of the Grulf of Manaar. 

 Among these were fifteen specimens of an organism which at 

 once struck me by its peculiar appearance, and which microscopic 

 examination soon showed to be no sponge. I have lately made 

 a careful investigation into the structure of this organism. At 

 first I felt certain that it was animal in nature, and commenced 

 my investigations from the zoological standpoint. I have, 

 however, been gradually forced to the conclusion that it is, at 

 any rate largely, of Bacterial origin. Not being a bacteriological 

 specialist myself, I feel some diffidence in offering the present 

 paper for publication ; but the organism in question is so 

 remarkable, and evidently forms such a conspicuous feature in 

 the marine life of the Grulf of Manaar, while at the same time 

 it presents such a striking resemblance in some respects to 

 certain obscure forms of life usually regarded as animal, that I 

 venture to hope the following description and suggestions may 

 be of some general biological interest. 



It seems desirable, for convenience of reference, to propose a 

 new generic name for the organism under discussion, and I 

 therefore name it Pontobolbos, from the Greek Troyros, sea, and 

 ^6Xj3os, bulb, in allusion to its marine habitat and concentrically 

 laminated structure. The question of generic diagnosis may be 

 conveniently left to the future. 



JPontoholbos manaarensis^ n. sp., forms hemispherical or cushion- 

 shaped masses, of a brown colour in the living condition, at- 

 tached to rocks in shallow water (PI. 26. figs. 1-4). The size of 

 the spirit-preserved specimens varies from 18 mm. to as much 

 as 36 mm. in diameter, and the colour is pale grey. The upper 

 surface is more or less convex, smooth and even, but very finely 

 granular in appearance. The lower surface, which has been 

 detached from the rock, is more or less flattened or even concave 



