112 Prof. W. Thomson on the Depths of the Sea. 



lyrura^ is about the same as D. Evelynce ; but the tail is dis- 

 tinctly forked, and its outer feathers are much longer, narrower, 

 and outcurved at the apex, while the remainder regularly 

 graduate towards the two central ones, which are very short. 

 When the tail is raised and the feathers partially spread, they 

 assume a lyre-like appearance, and hence the specific appella- 

 tion. Not wishing to depend upon my own judgment alone, 

 I submitted this bird to the inspection of Mr. Salvin, who, 

 after a careful examination, came to the same conclusion as 

 myself, that the bird is distinct, and that the form of the fea- 

 thers just described is the natural one. All my Nassau speci- 

 mens, as well as others I have seen from that district, have 

 the beautiful luminous lilaceous feathers confined to the throat, 

 while in the specimen sent to me through Mr. Lawrence, the 

 whole face is luminous, the metallic lilaceous colour extend- 

 ing across the forehead. 



Boricha lyrura^ Gould, n. sp. 



Forehead, throat, and breast beautiful shining lilac bordered 

 with blue, the two colours blending at their juncture ; imme- 

 diately below the gorget a band of greyish white, remainder 

 of the abdomen bronzy brown ; axilla3 rusty red ; wings pur- 

 plish brown ; upper surface golden green ; the narrow outer 

 tail-feather on each side black, the two next black on the 

 outer web, chestnut-red on the inner one, the next blackish 

 brown with green reflections ; the two middle ones green. 



Total length 3f inches, bill -j^g-, wing 1^, tail If. 



XIII. — On the Depths of the Sea. By Prof. Wyville Thom- 

 son, LL.D., F.R.S.* 



In the year 1864, and in succeeding years, G. 0. Sars, a dis- 

 tinguished son of the veteran and very distinguished Professor 

 of Zoology in the University of Christian ia, was employed as 

 a Commissioner of Fisheries in the service of the Swedish 

 Government ; and in his official capacity he had an opportu- 

 nity of dredging in deep water (300 fathoms) off the Lofoden 

 Islands, within the arctic circle. Instead of finding the bottom 

 of the sea barren at these great depths, as many circumstances 

 had led many of our most able naturalists to anticipate, he 

 brought up a multitude of animal forms, all of them of the 



* Communicated by the author, being the substance of a lecture deli- 

 vered, on the 10th of April, 1869, in the theatre of the Royal Dublin 



Society. 



