330 Linnean Society. [June 6, 



at the base of the other. The abdomen is singularly pitted on the 

 under side ; the surface of the carapace is covered with strawberry- 

 like tubercles, and the thick spines with which the legs are covered 

 are similarly ornamented. The most singular character however is 

 the absence of the hinder pair of legs, or (as the President suggested) 

 their apparent absence, there being no bole between the carapace 

 and abdomen through which these appendages could come. 



Mr. White gave a revision of the species of Lllhodes, which had 

 been much added to, since the work of Prof. Milne-Edwards, by a 

 Japanese species described by De Haan ; three species from Fuegia, 

 obtained on the voyage of Dumont D'Urville ; one described by 

 Edwards and Lucas ; another by Dana ; and another by Mr. White 

 himself. He proposed for the fine species obtained by Mr. Lobb, the 

 name of Lithodes (Petalocerus) Bellianus, in compliment to the Pre- 

 sident of the Society. 



Read also a Memoir " On the External Membrane of the Unim- 

 pregnated and Impregnated Ova of the Common Salmon." By John 

 Hogg, Esq., M.A., F.R.S., F.L.S. &c. 



In illustration of his paper, Mr. Hogg presented to the Society 

 two phials containing (preserved in spirit) mature ova as they fell, 

 from the female Salmon unimpregnated, and others taken at the same 

 time and artificially impregnated. They were taken by Mr. Harrison 

 in December last, and sent to Mr. Hogg in January by Isaac Fisher, 

 Esq. of Richmond, Yorkshire. " The ova in both phials," says Mr. 

 Harrison, " were taken from one fish in the River Tees, on the 27th 

 of Dec. 1853. The female fish was held up by the head, and when 

 the spawn was ready it run out by itself. The ova were with the 

 milt for about half a minute, or as soon as they could be got away. 

 The impregnation naturally takes place in a moment, as is always 

 the case in a stream, where the milt shed in the running water 

 passes rapidly over the ova." Mr. Hogg was unable to obtain either 

 the immature ova from the same female, or ova naturally fecundated 

 — two other conditions which he was desirous of examining to com- 

 plete the series of his observations. 



The object which Mr. Hogg had chiefly in view was the micro- 

 scopic examination of the external membrane of the ovum in these 

 several conditions, in relation to the statements made by different 

 authors as to its structure and the changes it is supposed to undergo. 

 Thus in the ' Book of the Salmon,' by Messrs. Fitzgibbon and A. 

 Young (Lond. 1850), it is stated (p. 183), that "the eggs of that part 

 of the roe nearest to the vent will be always found of larger size than 



