INTRODUCTION. 



Jelly-fish offer to the lover of natural history an inexhaustible store 

 of beauty and attractiveness. One who has studied them finds within 

 him a ready echo to Haeckel's statement that when first he visited the 

 seacoast and was introduced to the enchanted world of marine life, none 

 of the forms that he then saw alive for the first time exercised so powerful 

 an attraction upon him as the Medusas. The writer counts it a rare 

 stroke of fortune that he was led to the study of a portion of the group 

 by the discovery of two new species of Cubornedusae in Kingston Harbor, 

 Jamaica, W. I., while he was with the Johns Hopkins Marine Laboratory 

 in June of 1896. 



The Cubomedusae are of more than passing interest among jelly-fish, 

 both because of their comparative rarity and because of the high degree 

 of development attained by their nervous system. One fact alone suffices 

 to attract at once the attention of the student of comparative morphology 

 that here among the lowly-organized Coelenterates we find an animal 

 with eyes composed of a cellular lens contained in a pigmented retinal 

 cup, in its essentials analogous to the vertebrate structure. Perhaps this 

 and other facts about the Cubomedusae would be more generally known, 

 had they not been to a certain extent hidden away in Claus's paper on 

 Charybdea marsupialis ('78), which, while a record of careful and accu- 

 rate work, is in many respects written and illustrated so obscurely that 

 it is very doubtful whether one could arrive at a clear understanding of 

 its meaning who was not pretty well acquainted with Charybdea before- 

 hand. 



Before Claus's paper was received at this laboratory, H. V. Wilson 

 went over essentially the same ground upon a species of Chiropsalmus 

 taken at Beaufort, N. C. When the article on Charybdea marsupialis 

 appeared, however, the results were so similar that Wilson did not com- 

 plete for publication the careful notes and drawings he had made. 



Haeckel's treatment of the Cubomedusas in his " System " ('79) in the 



Challenger Report ('81) is much more lucid than Claus's ; but the extended 



scope of his work and the imperfect preservation of his material prevented 



a detailed investigation, and for a more complete and readily intelligible 



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