0)1 the Structure of the Graafian Follicle in Didelphys. 407 



16. Alca torclct, Linn. — Razorbill. — Harvie-Brown speaks 

 of the razorbill as " common to the exclusion as far as we 

 could see of the guillemots, occupying the broken and 

 irregular sea-cliffs, especially on the east side of No. 2 

 (Eilean Craigeach). I counted twenty- three in the air at one 

 place at the same time." 



As far as my own observations have gone, they incline me 

 to the belief that the razorbill builds or rather lays its eggs 

 on lower and less perpendicular cliffs than the guillemot, 

 although it is also found associating with the latter at all 

 the great breeding stations. 



. 17. Uria grylle (Linn.) — Black Guillemot. — This bird was 

 very common on all the islands, but, as before stated, it simply 

 swarms on Eilean Eashal. Harvie-Brown estimates the 

 number of black guillemots breeding on the Ascrib Islands at 

 250 pairs, and I cannot say that I think the estimate too high. 



18. Fratercula arctica (Linn.) — Puffin. — Common upon 

 both Eilean Eashal and Eilean Craigeach. On the former 

 it was to be found among the black guillemots under the slabs 

 and boulders that fringe the island ; on the latter, where it 

 w^as much more abundant, it bred in holes in the grassy ledges 

 of the cliffs, also about their tops. They have assisted in the 

 extermination or decrease of the storm petrel on the South 

 Ascrib, as Captain Macdonald informed Harvie-Brown. 



Ohs. — Harvie-Brown saw some ducks, but, owing to a haze 

 which prevailed at the time, they could not be satisfactorily 

 identified. 



XXXIII. On the Strncture of the Graafian Follicle in 

 Didelphys. By Feank E. Beddard, Esq., M. A., F.E.S.E., 

 Prosector of the Zoological Society, and Lecturer on 

 Biology at Guy's Hospital. 



(Read 18tli January 1888.) 



The earliest memoir known to me which deals with the 

 structure of the ovarian follicle in marsupials is a recently 

 published account ^ of these structures by Mr Poulton. This 



1 The Structures connected with the Ovarian Ovum of Marsupialia and 

 Mouotremata {Quart. Journ. Micro. Sci., 1884, p. 1). 



VOL. IX. 2 E 



