349 THE ZOOLOGIST. 
health; they now therefore must be more than seven years old, being 
by far the oldest insects on record. 
Dwarr Swiwmine Crap at Penzance.—After waiting for it many 
years, I have at length obtained a specimen of the Dwarf Swimming Crab, 
Portunus pusillus. I do not know, nor shall I be able to discover, where it 
came from, but as I found it on my doorstep in the heart of Penzance, I 
may assume that it probably came from Mount’s Bay. It is a large speci- 
men, but I do not give measurements because, having been flattened by the 
pressure of some heavy substance, probably a fishwoman’s “cowel” or 
basket, it looks larger than it was in life. It is unfortunately unfit for 
preservation, but not by any means damaged beyond identification.—THos. 
CornisH (Penzance). 
DEVELOPMENT oF THE CrENopHoRA.—In accordance with his usual 
practice of making his anniversary address an exposition of recent progress 
in some department of zoological research, the President (Prof. Allman), 
at the meeting of the Linnean Society on May 24th last, selected as his 
subject the advances which during late years had been made in our know- 
ledge of the development of the Ctenophora, those gelatinous transparent 
organisms which swim by means of rows of cilia, mostly disposed in 
comb-like plates, or ctenophores. He referred especially to the beautiful 
researches of Alexander Agassiz, and to those of Fol, Kowalewsky, and 
most recently of Chun. He pointed out the phenomenon to which he 
was himself the first to call attention, that immediately after the earliest 
stages of the egg-cleavage a remarkable peculiarity shows itself, in the fact 
that the cleavage is no longer uniform, but takes place more energetically 
in certain cleavage spheres than in other, whereby the former are broken 
up into a multitude of small cells which gradually envelop the latter, thus 
giving us at this early period of embryonic development the foundation of 
the two germinal leaflets, ectoderm and endoderm. He showed how the 
body thus formed becomes excavated by an external cavity which soon 
communicates by an orifice with the exterior, thus presenting, as shown 
especially by the researches of Chun, the condition of a gastrula; how the 
gastrula-mouth becomes afterwards closed by the continued extension over 
it of the ectoderm; how a new orifice, the permanent Ctenophore-mouth 
makes its appearance at the opposite hole, the ectoderm here becoming 
invaginated so as to form the permanent stomach which opens into the 
central cavity, which becomes the “funnel” from which spring all the 
vessels which are destined to distribute the nutritive fluid through the 
body; how in the spot formerly occupied by the gastrula-mouth certain 
cells of the ectoderm become differentiated so as to form the rudimental 
