TRANSACTIONS OF THE SECTIONS. 79 
List of the Names of Periodical Birds, and the dates of their appearance and 
disappearance, at Llanrwst, in North Wales. By Joun BLACKWALL, 
FILS. : 
Mr. Gould exhibited several new species of humming-birds from the Andes. 
On the Figures of Birds observed on a Tomb at Memphis. By J. Bonomi. 
Since his last communication the author had received the following note from Mr. 
Moreing :—* The gigantic nests to which you refer, were seen by me in the years 
1829 and 1830, during the time I was attached to the Surveying Expedition in the 
Red Sea. 1 do not remember having seen them to the south of Cossier, but to the 
north of that town, and about the entrance to the Sea of Suez, I observed many. 
They were always situated cn the small sandy spits and islands with which the Red 
Sea abounds ; but you are mistaken if you suppose them to be entirely the work of 
the birds which breed in them. They varied both in size and height, and were 
evidently formed in the first instance by the wash of the sea heaving up pieces of, 
broken coral, drift wood, and other rubbish on the extremity of a sand spit. ‘The 
birds added to the mound thus formed; and placed their nests on the top, to pro= 
tect themselves from the spray in rough weather. I am not clear as to the species 
of bird which make use of these singular nests, but believe that more than one kind 
of gull avail themselves of the security thus offered.” 
On the Crania of two species of Crocodile from Sierra Leone. 
By H. Fatconer, M.D. and W. THompson*. 
Crocodilus cataphractus, Cuv. and C. vulgaris, Cuv. (var. C. Dumeril and Bibron), 
were the species noticed; the cranium of the former, divested of its integuments, 
being now for the first time described. The differences between the cranium of the 
latter and that of allied species were noticed in detail in the paper, which was 
illustrated by figures of the crania of the two forms from Sierra Leone, whence the 
specimens were brought by Dr. M‘Cormac of Belfast, and presented by him to the 
museum of that town. 
Recollections of Researches into the Natural and Economie History of certain 
Species of the Clupeade, Coregoni,and Salmonide. By R.Knox, M.D. 
The author stated that his object was to bring before the Association, and after- 
wards before the Academy of Sciences of Paris, a brief view of the inquiries made by 
himself and his brother into the natural history of certain important gregarious 
fishes. His discovery that the food of the Vendace or Vengis, of Lochmaben, con- 
sisted exclusively of the minute, or rather microscopic Entomostraca inhabiting the 
lakes of Lochmaben, was first communicated to the Royal Society of Edinburgh. 
This discovery, which at the time appeared to the author and to a few others of the 
highest importance in natural history science, had, in his opinion, been misunderstood 
by the public, and by most naturalists to whom he had spoken; they adhering to 
the old opinion, that certain fishes, to be afterwards spoken of, preyed on the Ento- 
mostraca merely occasionally; at other times on small shell-fish, animalcules, minute 
or smali fishes, &c., just as they could get them: which opinions the author endea- 
voured to show were contrary to tle facts. After discovering that fishes so nume- 
rous, so productive and of such a size as the Vendace, subsisted solely on one de~ 
scription of food, the Entomostraca,—a sort of food over which man can exercise 
little control, especially in the ocean,—the author knowing that, up to his time, the 
real food of the herring and of several other species of fish had never heen dis- 
covered, prosecuted his inquiries into this important branch. The result was the 
discovery that, whilst the Vendace lives exclusively on the Entomostraca, the same 
may be said of the herring ; that is, of most of its varieties. The finer kinds of lake 
_ trout, also the Char, live chiefly on the Entomostraca. Dr.Knox gave an outline of 
_ * Published in full, accompanied by illustrations, in the Annals of Nat. Hist. for Dec. 1846, 
