Miscellaneous. 179 
I can only, then, again assure my friend Mr. Butler. that, because 
I do not support his charge against the Felders, I do not necessarily 
bring one against him ; and he will probably agree with me that the 
whole of this unsavoury discussion is detrimental to the cause of even 
descriptive entomology, and affords further proof of the injury done 
to the same by personal competition. 
‘On some Experiments in Hybridization between different Species of 
Kchinoidea. By M. R. Koutzr, 
Experiments on the hybridization of Kchinoderms have been 
_ hitherto but few in number. In 1873 M. Marion published 
(‘Comptes Rendus,’ April 14) an account of fecundations effected 
between Strongylocentrotus liwidus and Spherechinus granularis, 
which resulted in the production of perfectly developed Plutei. A 
year later Agassiz announced, in the ‘ Archives de Zoologie Expéri- 
mentale,’ a case of hybridization between two species of the genus 
Asteracanthion, in which the larvee attained the stage of Bipinnaria. 
At the suggestion of M. Marion I have resumed these experiments 
in the laboratory of marine zoology at Marseilles; and their results 
possess some importance in connexion with the physiology of the 
species, which was, indeed, indicated by M. Marion in his note pre- 
sented to the Academy. These new experiments in hybridization 
have been extended to several species of regular and irregular sea- 
urchins. J cannot here give a complete analysis of these fecunda- 
tions, which will be studied in detail in my memoir on the Echi- 
noidea of the shores of Provence. I shall therefore content myself 
with indicating the definitive results at which I have arrived. 
In March and April the products of the genital glands in most 
of the species of Marseilles have generally arrived at maturity ; 
nevertheless it is not unusual to meet with individuals of which the 
ovules or spermatozoids, still immature, are unfit for any attempt at 
fecundation. It is therefore indispensable to precede each expe- 
riment by a microscopic observation. It is equally important to 
make, in parallelism with each crossed fecundation, a direct fecun- 
dation under the same conditions, and with products belonging to 
the same individuals, for the purpose of arriving at comparable 
results, both as to the state of the larva and the time it takes to 
arrive at a definite stage in both: cases. 
The following is a list of the experiments made, with the results 
obtained in the most successful fecundations :— 
Strongylocentrotus lindus 9 and Spherechinus granularis 3 .— 
Pluteus regularly and perfectly developed. 
Id. and Psammechinus pulchellus §.—Pluteus always well de- 
veloped. 
Id. and Dorocidaris papillata §.—The ova, of which a very 
small number were fecundated, did not pass the blastula stage. 
(It is true the only living Dorocidaris I had at my disposal had 
been captured some time, and its spermatozoids were not very 
active.) 
Strongylocentrotus 9 and Spatangus purpureus $ .—Many nega- 
tive experiments ; fecundation, however, is possible, but the fecun- 
