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TRANSLATIONS. 



On the MoKPHOLOGY of the Copepoda. By C. Claus. 



(From Wiirzburgerj Naturwissenschaftliclie Zeitsclirift. I, p. 20. 1860.) 



I. A Case of Monstrosity in Cyclops (Plate X, figs. 1 and 2). 



The observation of a minute Cyclops, scarcely two thirds 

 of a millimetre in length, and yet furnished with ovisacs con- 

 taining developed embryos, made me suppose, at first sight, 

 that I had fallen in with a new species of the genus. Closer 

 investigation, however, showed that this sexually developed 

 individual represented a stunted or arrested form of growth, 

 which, from the variety of similar cases among the Ento- 

 mostraca, is worthy of notice, and the more especially 

 so since the known processes attending the free metamor- 

 phoses in Cyclops throws some light upon the origin and 

 cause of this malformation. 



The essential morphological distinctions of the sexually- 

 mature Cyclopida are derived from the definite number and 

 regular articulation of the somites and their appendages. 

 The same value which in the Vertebrata attaches to the 

 number or form of the vertebrae in the characterization of 

 the various regions of the body, also attaches to the number 

 and differences of the segments in the different divisions of 

 the body in the Arthropoda. However numerous and 

 various may be the differences under which the numerous 

 modifications in form and structure of the arthropod body 

 are exhibited, equally regular appears to be the division of 

 the body in the various orders and families, and as constant 

 and immutable the number and relative size of the somites 

 within the more restricted compass of the genera and species. 

 With respect to the Cyclopida, I endeavoured in a former work 

 ('ZurAnatomieundEntwickelungsgeschichte der Copepoden. 

 Archiv f. Naturg.,^ 1858) to determine the law of uniformity 

 in the morphological development of the body, and to this 



