212 



compliqués pour arriver aux plus simples. L'emploi des hypothèses 

 m'a toujours paru le meilleur moyen d'arriver à l'observation des 

 faits; mais je considère comme entièrement illusoire et absolument 

 chimérique toute hypothèse qui échappe nécessairement au contrôle 

 de l'observation ou de l'expérience. Il n'est pas, selon moi, de mé- 

 thode moins scientifique que celle qui consiste à faire de ces hypothè- 

 ses invérifiables l'objet même de la science. La connaissance des faits, 

 tel est le véritable but de la science: tout le reste n'est bon qu'à servir 

 de moyen d'étude. 



Grenoble, le 22 mars 1892. 



3. On a new species of Cassiopea from Jamaica. 



By R. P. Bigelow, Bruce Fellow in the Johns Hopkins University. 



eingeg. 25. März 1892. 



Cassiopea œamachana ^ nova species. 

 Diagnosis. The umbrella is concave on the aboral side forming 

 a sucking disk. The number of rhopalia is regularly 16, but often 

 from 17 to 23. When there are 16 rhopalia, there are 80 short, obtuse 

 lobes in the margin of the umbrella, separated by deep grooves on the 

 exumbrella surface (in each of the 16 parameres, 3 velar lobes between 

 2 ocular ones) . The exumbrella is marked by a white circle at the 

 periphery of the concavity , from this there extends outward a white 

 band along each marginal lobe, and in the radius of each rhopalium 

 there is also a white band tapering centrally from this circle to a point 

 about half m ay to the stomach. These radiating bands are not always 

 connected with the circle of white. The eight oral arms are rounded 

 and slender, never angular, with 10 to 15 alternate primary branches 

 and numerous secondary ones. The distance from the centre of the 

 oral disk to the tip of an extended arm nearly equals the diameter of 

 the umbrella. In the axil of each branch there is a flattened oval or 

 linear vesicle varying in length with the size of the adjoining branch, 

 the length of the eight largest ones (one in the axil of the chief branch 

 of each arm) sometimes equaling 1/4 the diameter of the umbrella, 

 while many do not exceed the size of one of the oral funnels. There 

 are also 5 to 13 large vesicles on the oral disk, the one in the centre 

 being the longest. In full grown individuals there are no oscula or 

 oral funnels on the oral disk except near its margin. Their place is 

 taken by a great number of very small oval vesicles. 



1 This name was suggested by Professor Brooks and is derived from the an- 

 cient Indian name for the Island of Jamaica. 



