12 



nnci forty i^ pec i mens hehnfjinfj to thirty-eight specios infested ivith Choniostomafidcp, hit neither 

 on these, nor on any other of the thousands of individuals belonging to these thirty-eight 

 species, have I found one single Epicarid. So we have done with thirty-eight of my species 

 of Choniostomatidse, and of the five remaining species two may be passed over, viz. tlie species 

 of the genus Mysidion, for neither I nor any other author have found any Epicarid in the 

 marsupium of the hosts of Mysidion, viz. the genera Erythro^ys and Parerythrops. Only on 

 the outside of the body of the species belonging to the genus Erythrops, and in the branchial 

 cavity of two species of Hippolyte, others as well as myself have found altogether three 

 species of Choniostomatidse, and at the same time species of Epicaridea. As a rule the 

 animals of each order were found on separate specimens; in one case observed by myself, 

 and in one case mentioned by Giard and Bonnier, animals of both orders were found on the 

 same specimen. Still it can be proved that these two quite diiferent types of parasites, 

 though perhaps in very rare cases they may be in each others way, stand at least in no 

 other mutual relation. As for Ghoniostoma Hansenii, I can prove that the animal itself 

 produces the .swelling on the carapace (comp. my special description of this animal), and in 

 the only case where Ghoniostoma and Gyge were found on the same side undei- the carapace, 

 a male and a still smaller female of the latter genus had lodged themselves in a large 

 swelling, which was inhabited by an adult female Choniosfoma with eleven ovisacs. As for 

 the last of my species — Aspidoecia Normani — I have fouiul it on twenty-one specimens 

 of all five species of the genus Erythrops, but I found no Epicarid on any of these animals. 

 Moreover, the occurrence of Aspidoecia, not only on the shield, but also on the exterior side 

 of the thorax and on the six abdominal segments, as well as on the eyes, proves sufficiently 

 that it stands in no comiection whatever with Aspidophryxus , wliich parasite lives only 

 on the carapace. 



Immediately aftei' the paragraph criticised above the authors write: »Toutes ces 

 considerations sont sans doute fort hypotlieti(|ues, mais elles peuvent inspirer de nouvelles 

 recherches et indi(jner la voie aux investigateurs. Elles ont de plus I'avantage de rattacher 

 par un lieu 6thologi([ue comniun les types de Copepodes si 6tranges qui constituent la famille 

 des Ghoniostomatidff!"^. This »lien 6thologi(iue« is (juite broken now and will scarcely ever 

 be restored. As for the first part of the ([notation, I regret to say that it has indicated 

 no path to me, and that, far from having been inspired by their , consid6rations« , 1 have 

 been obliged to waste time and space upon proving the untenability of some unwarranted 

 hypotheses. To suggest sucli hypotheses indeed is not very difficult, and most zoologists 

 have imagination euongli to invent scores of them. If productions of this kind had any real 

 value, it would be easy to promote the progress of science. But I confess that, though I 

 honour everybudy wIkj is cai)able of suggesting a theory which proves to be well founded 

 and fertile in results, I have always felt and, as time goes on, feel more and more distaste 

 for superficial conjectures. 



