192 JURA. LUMINOUS ANIMALS. 



in which these animals do not exist, is originally derived 

 from the same source. This list will be found at least 

 as large as could have been expected, when we consider 

 the small number of observers, the difficulty of the circum- 

 stances under which the observations are made, and, still 

 more, the neglect which the subject has experienced from 

 the causes already stated. 



In the class Crustacea several species have been found 

 luminous ; as the Galathea amplectens of Fabricius, ob- 

 served on the coast of Brazil by Sir Joseph Banks, and 

 the Astacus fulgens of the same author ; besides several 

 genera of the family Gammaridere, according to the obser- 

 vations of Hablitzl and Professor Jameson. In the genus 

 Beroe, now included in the family of the Medusae, the 

 fulgens has derived its name from its luminous quality; 

 and I am further informed by Mr. Giesecke, that he has 

 observed many different and unknown species of this 

 genus on the coast of Greenland, which are not only lumi- 

 nous when alive, but retain this property when broken 

 to pieces by the surging of the sea ; scattering a splendid 

 and iridiscent light over its surface. The same naturalist 

 has described another lucid animal hitherto unnoticed, 

 which he calls Cyclops brevicornis (Monoculus brevi- 

 cornis ?) and Riville has made us acquainted with another 

 also of this tribe, possessing the same property, which he 

 has called the Monoculus lynceus ; but the true Mono- 

 culus lynceus (the Lynceus brachiurus of Muller) inhabits 

 fresh water. 



There is no question that the Nereis noctiluca emits 

 light, since it has been examined by many observers. 

 Having also been nearly the first species ascertained to 

 afford this appearance, it has probably been one cause 

 of the neglect which naturalists have shown of the other 

 luminous animals; every effect of this nature being ascribed 

 to it, and the investigation of the individual consequently 

 neglected. Another marine crustaceous animal, under the 



name of Limulus noctilucus, is described as luminous in 

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