THE MYSID^ 267 



maxillipeds tave usually a natatory exopod, and an epipod 

 projecting within the branchial cavity. The second pair are 

 modified to serve the mouth. The remaining appendages 

 of the trunk are uniform, rather feeble, the terminal part 

 generally subdivided into short setiferous articulations, 

 the finger being small or wanting. There are no true 

 branchise. The marsupium is composed of seven or more 

 often of only two or three pairs of plates. The pleo- 

 pods in the female are as a rule quite rudimentary, in the 

 male either natatory or modified for sexual purposes. The 

 inner branch of the uropods usually contains an audi- 

 tory apparatus. The development is without any free 

 metamorphosis. 



The eighteen genera included in this family by Sars 

 in 1885 are Mi/sis, Latreille, 1803, Siriella^ Dana, 1850, 

 Promysis^ Dana, 1850, Andddlus, Kroyer, 1861, Iletero- 

 my sis, S. I. Smith, 1874, Petalophthalmus, v. Willemoes 

 8uhm, 1879, and the following twelve all instituted by 

 Sars himself, Amhlyopsis, Boreomysis, EryiliroiDS, Hemimysis, 

 Leptomysis, Mysideis, Mysidojms, Parerythrops, Pseudomma, 

 under the common date of 1869, Mysidella, 1872, Meter opsis, 

 1876, and Euchcetomera, in 1883. The list (no doubt acci- 

 dentally) omits a nineteenth genus, PsPMdomy sis, Sars, 1880, 

 and a twentieth, GastTOsaccus^ Norman, 1869, from which 

 yet another has been severed in Haplosti/his, Kossmann, 

 1880. From Siriellci Claus has separated Pseudosiriella, in 

 1884. YvoiR Mysideis Norman in 1892 distinguishes 8tilo- 

 mysis, and in the same year recognises Macromysis, White, 

 1847, Neomysis, Czerniavsky, 1882, and a new genus 

 8chistomysis, as distinct from My sis. Thus with Arctomy- 

 sis, Hansen, 1887, added since Sars drew up his list, and 

 with Arachnomysis, Chun, the number of genera, if all are 

 accepted, amounts to twenty-eight. But further, Nor- 

 man has called my attention to Czerniavsky 'sMonographia 

 Mysidarum, 1882-3, in which several new but not always 

 well-founded genera appear. One of these preoccupies the 

 name Ardomysis, so that Hansen's genus must be re-named. 

 Macromysis also must yield to the rather queer but much 

 earlier generic name Praunus, Leach, 1813, of which the 



