THE OTTAWA NATURALIST. 



Vol. X. OTTAWA, APRIL, 1896. No. i. 



REMARKABLE POINTS IN THE LIFE-HISTORY OF 

 PHYLLOPODS. 



By I'rofessor E. E. Prince. 

 Dorainion Commissioner of Fisheries, Ottawa. 



The brief but interesting notes on Ottawa Phyllopods, con- 

 tributed to these pages by Mr. Andrew Halkett in July last, 

 refer to crustaceans cf such singular scientific interest that some 

 additional observations may not be out of place. The Order 

 Phyllopoda includes the crab-like form Apus, believed to closely 

 resemble the ancestors of the Class Crustacea, and others like 

 Liinnadia, Artemia^ Branchipus and Daphnia, the last (" the water 

 flea ") being one of the most enchanting of living objects under 

 the microscope, and presenting in its eggs and life-history, many 

 interesting points to the biologist. 



It is to the shrimp-like Branchipus, and Arternia, that the 

 present notes will be mainly confined. In the first place, the 

 structure of the eye, as Mr. Halkett pointed out, is of the most 

 striking character. It is not a mere black spot seated in the 

 skin, as it is in Daphnia, nor is it a completely stalked moveable 

 eye, as in the shrimp and crab ; it is in fact neither sessile nor 

 stalked ; but intermediate between the two, and forms a fixed 

 protruding organ foreshadowing in its form and pseudo-facetted 

 character the stalked compound eye of the lobster. No organ 

 of vision in the Class Crustacea is of a more profoundly interesting 

 character. It shows the sessile eye in process of transformation 

 into a prominent stalked eye, a remarkable illustration of 



