THE MYSIDJE 267 



maxillipeds have 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 

 branchiae. 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 Mysis, Latreille, 1803, Siriella, Dana, 1850, 

 Promysis, Dana, 1850, Anchidlus, Kroyer, 1861, Hetero- 

 mysis, S. I. Smith, 1874, Petalophthcdmus, v. Willemoes 

 Suhm, 1879, and the following twelve all instituted by 

 Sars himself, Amblyopsis, Boreomysis, Erythrops, Heminvysis, 

 Leptomysis, Nysideis, Mysidopsis, Parerythrops, Pseudomma, 

 under the common date of 1869, Mysidella, 1872, Macropsis,. 

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

 dentally) omits a nineteenth genus, Pseudomysis, Sars, 1880, 

 and a twentieth, Gastrosaccus, Norman, 1869, from which 

 yet another has been severed in Haplofitylus, Kossmann, 

 1880. From Siriella Glaus has separated Ps&udosiriella,, in 

 1884. ~Frorn Mysideis Norman in 1892 distinguishes Stilo- 

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

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

 Schistomysis, as distinct from Mysis. Thus with Arctomy- 

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

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

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

 man has called my attention to Czerniavsky 's Monographia 

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

 well-founded genera appear. One of these preoccupies the 

 name Arctomysis, 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 



