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sufficiently advanced to enable the question to be definitely 

 settled. It apparently did not occur to Hesse to attempt to 

 ascertain the sex of these forms by dissection. Arguments 

 are adduced at considerable length to prove by circum- 

 stantial evidence that certain forms are males and others 

 females, while not a single attempt to determine the sex of 

 any specimen by direct observation is recorded. We do 

 not certainly know but that Hesse's specimens of Ncesa, 

 Dynmnene, and Cymodoce all contain both male and female 

 forms. The question may easily be determined without 

 having recourse to internal dissection, as the males of the 

 Sphaeromidae may be recognized by the presence of a 

 stylet on the inner ramus of the second pair of abdominal 

 appendages. 



As Dynamene is supposed to represent the female form 

 of NcBsa, Hesse assumes that it should rank as a synonym 

 of the latter; all of the species he describes, some of which 

 are known only from the female, or Dynamene form, are 

 placed under the genus NcBsa. According to the rules of 

 the American Ornithologists' Union, which are largely fol- 

 lowed in this country, if two names are given simultaneously 

 to the same genus and are otherwise of equal pertinency, the 

 name based on the adult male takes precedence over that 

 based on the young male or female. Nescea and Dynamene 

 were both instituted by Leach in the article 'Crustaceology ' 

 in the 'Edinburgh Encyclopedia' in 1814. Other things 

 equal, Nescea, being based on the male form, would be 

 retained; but other things were not equal, the names were 

 not of equal pertinency, as Nes(sa was preoccupied. Ncesa, 

 which was substituted for Nescea (nomen freocc.) in 1818, 

 becomes, if based as the male of Dynamene, a synonym of 

 the latter genus. The same result would be arrived at by 

 following most of the other codes of nomenclature now in 

 vogue. 



On the other hand, the retention of Dynamene may be 

 objected to on the ground that, as no species were assigned 

 to it, it was not properly defined, and should be considered 

 indeterminate. According to canon 37 of the code above 



