164 BULLETIN 201, UNITE,© STATEIS NATIONAL MUSfEUM 



was referred to the same genus. In 1882 Czerniavsky established the 

 genus Onychomysis for the species O. mingrelica, and without the 

 examination of specimens he referred Mysis latitans Kr0yer to the 

 same genus. Mysis latitans is, however, synonymous with the earlier 

 species Mysis mixta Lilljeborg and has no obvious affinity with 

 Czerniavsky's species. 



In 1902 Norman separated Mysis mixta from the genus Mysis and 

 made it the type of the new genus Michtheimysis because of the un- 

 jointed and acutely pointed antennal scale and the form of the male 

 pleopods as figured by Sars. Zimmer (1915a) pointed out that Sars' 

 figures of the male pleopods of Mysis oculata were drawn from imma- 

 ture specimens, and that in the completely adult male they were al- 

 most identical with those of M. mixta. He regarded the character of 

 the scale of M. mixta to be insufficient as a generic character alone 

 and canceled the genus Michtheimysis as a synonym of Mysis. Later 

 authors have used either generic name indiscriminately. In this paper 

 I follow Zimmer's lead and retain M. mixta and M. stenolepis in the 

 genus Mysis with M. oculata and M. relicta. I would point out, how- 

 ever, that a precisely parallel state of affairs occurs in the genus 

 Neomysis where there are two groups of species separable on the char- 

 acter of the antennal scale. One group has the scale produced into an 

 acute apex, the other group has the scale jointed, with the apex 

 rounded. The former group is the genus Neomysis (sensu stricto) 

 and the second group the genus Acanthomysis. Zimmer unites these 

 two groups of species under the genus Neomysis on the grounds that 

 the form of the male pleopods in each is identical. In 1933 I pointed 

 out that the genus Neomysis {sensu lato) was becoming too unwieldy 

 and that as a matter of convenience it might be perhaps desirable 

 to reinstate the genus Acanthomysis. This has since been done by Ii 

 (1937). The plea of expediency can hardly be raised in the genus 

 Mysis, and for the present at least I am content to accept Zimmer's 

 conclusions. 



In 1905 Norman, I believe inadvertently, used the generic name 

 Mesomysis for the species M. mixta and M. stenolepis, without giving 

 any reasons. Czerniavsky's genus Mesomysis is, however, quite dis- 

 tinct in the characters of the antennal scale, having the outer margin 

 entire and not setose. 



Dr. Mary J. Rathbun called my attention to a paper by Leach 

 (1830, p. 177) in which he describes a crustacean under the name of 

 Megalophthalmus fabricianus. The description is very imperfect, but 

 I strongly suspect it refers to Mysis oculata. Cancer pedatus Fabri- 

 cius is given by Leach as a synonym of his species. The species is 

 said to be abundant oif the coasts of Greenland, especially in Baffin 

 Bay. From the meager description the species is almost certainly a 

 mysid and in all probability Mysis oculata. 



