366 MR. A. DOBAN ON THE 



Grenus LEPTASTHiEA, Milne-JEdwards Sf Jules Haime. 



This is a genus typical of incrusting and solid Aporose Astrseidse, 

 and tlie species are very well characterized by their thick inter- 

 corallite walls and intercorallite tissue. In a species from Mergui 

 many scores of corallites of 5 or 6 millim. in height covered the 

 uneven surface of a piece of conglomerate ; and it is evident that 

 although extracalicular gemmation occurs in a few instances, the 

 majority of the corallites grew side by side from a basal structure, 

 and usually upwards in a vertical line. The base is not a wall, 

 but a very thin epitheca; and there is no true wall. 



There is no doubt that this epithecal rejDlacement is very 

 common in the incrusting species of most genera ; and the 

 peculiar increase of the corallum is at first by growth from the 

 common epithecate basal expansion and then by gemmation from 

 the wall of the corallite. 



On the Auditory Ossicles of Bhytina Stelleri. By Alban Doran, 

 F.E.C.S. (Communicated by Professor "W. H. Flower, 

 F.E.S., r.L.S.) 



[Eead December 20, 1883.] 



Ik a recent monograph contributed to this Society and published 

 in its Transactions*, I described the characters of the auditory 

 ossicles of the Mammalia, having succeeded in procuring for the 

 purposes of description and study a very large series of these 

 little bones, which now constitute a special collection, preserved 

 in the Museum of the Eoyal College of Surgeons of England. It 

 was only with regard to a very few species indeed that I was com- 

 pelled to rely upon descriptions found in the works of compara- 

 tive anatomists; for where the vast resources of the College, 

 kindly placed at my disposal by Professor Plower, failed to en- 

 lighten me, I generally succeeded in borrowing the desired ossicles 

 from other collections. In describing the ear-bones of the Sirenia, 

 however, I had to rely entirely on description in the case of Rhy- 

 tma, my source of information being a paper by Claudius entitled 

 " Das Gebororgan von Uliytina Stelleri,^'' published in the ' Me- 

 moires de TAcademie des Sciences de St. Petersbourg,' 1867. 

 Claudius describes the malleus very clearly ; but ever since the 

 publication of my own monograph, I have been seeking an oppor- 



* " Morphology of the Mammalian Ossicula auditus," Linn. Soc. Trans. 2ad 

 ser. Zoology, vol. i. pp. 371-497, pis. 58-64. 



