304 Chronicles of Science. [ April, 
numbers from the refuse of some sugar works, associated with 
Anguillula, Podwra, and other vermin. They belong to the genus 
Sciara, and it is worth noting that these observations were made 
at a distance of some 350 leagues from the locality of Professor 
Wagner’s researches. Professor Pagenstecher described most 
minutely the anatomy of these larve. He differed from Professor 
Wagner as to the nature of the fatty bodies, and believed that the 
germs are formed independently of these bodies, but afterwards 
assimilate them as other nutritive matters. The exact position in 
which the eggs are developed he could not ascertain, but 1t appeared 
to be near the junction of the Malpighian vessels with the intestine. 
The gradual growth of the young larve inside its parent he most 
carefully describes, and it appears to moult while still in the egg ; 
meanwhile the parent larva moves less and less, but still remains 
well and living, though largely distended. At length she assumes a 
new skin, which is harder and more chitinous than the last. The 
young, who have now escaped from their eggs, commence to devour 
her viscera, and at last finish by reducing their parent to the con- 
dition of a yellow larval skin filled with young grubs, which shortly 
escape. Professor Pagenstecher had no doubt that a complete 
analogy exists between this case of parthenogenesis and that of 
Aphis, and hence differed from Professor Wagner. On the 2nd 
of March last year a paper by M. Hanin of Charkow, on this same 
subject, was read at the Academy of Sciences of St. Petersburg. 
The larvee he had studied were found under the planks of a house 
in the débris of various edibles. M. Hanin has verified Professor 
Pagenstecher’s opinion that the ovules are produced by special 
organs; they are not simply developed in the corpus adiposum, but 
are produced in little sacs, to which he gives the name of ovaries. 
It must be remembered, at the same time, that these ovules or eggs 
are pseudova, and not true ova, as far as we know. M. Hanin’s 
paper is especially valuable on this account, that he describes the 
development of the pseudova, and thus completes the history of 
this very remarkable case of agamic reproduction. 
Dr. Lacaze-Duthiers describes a new and very remarkable genus 
of Ascidians in a late number of the ‘Annales des Sciences Natu- 
relle:, for which he proposes the name Chevreulius. There can be 
little doubt, as the author remarks, that this genus will form the 
type of a new group of Ascidia. It presents the very peculiar 
character of an Ascidian with a bivalve test, and hence offers an 
approach to the Brachiopoda in its external conformation ; the lower 
valve being much the largest, and not differmg much in appearance 
from that of some Thecidia. The minutest details of structure and 
life-history are given by M. Duthiers in this most elaborate essay 
on the genus. The chief point of interest in the little Chevreulius 
is the confirmation which it affords to the opinion of Messrs. Huxley 
.) . 
