A REVIEW OF THE MYSIDACEA 203 



NEOMYSIS MERIDIONALIS Colosi 



Recorded on page 247. 



NEOMYSIS MONTICELLI Colosi 



Records of this species are given on pages 248. 



Genus ACANTHOMYSIS Czerniavsky 



Acanthomysis Czerniavsky, 1882a, pp. 58, 64, 134. — Ii, 1936a, p. 588. 

 Dasymysii Holt and Beaumont, 1900, p. 245. 

 Met amy sis Nakazawa, 1910, p. 250 (nee Sars, 1895). 

 Orientomysis Dershavin, 1913, p. 200. 



As stated above I accept Ii's restoration of this genus to include 

 those species hitherto referred to Neomysis in which the antennal 

 scale is rounded at the apex and not produced into a spine. It is 

 significant that no species of this genus has yet been found to possess 

 sternal processes on the last two or three thoracic sterna in the female. 

 This may prove an additional generic character when all the species 

 of the genus Neomysis (sensu stricto) have been examined for this 

 point. The baling lobe on the anterior oostegite is present but not so 

 well developed as in Neomysis. 



Seven species of this genus are known from American waters. They 

 may be separated according to the key. 



KEY TO THE AMERICAN SPECIES OF ACANTHOMYSIS 



o l . Supraocular spine on carapace; incipient grooves on last thoracic and first 



three abdominal somites columbiae (p. 204) 



a K No supraocular spine on carapace. 



b K Grooves well marked on all abdominal somites. 



c 1 . Fourth abdominal somite with a dorsal median posterior spine; fifth 

 abdominal somite with a dorsal median posterior spine and a strong 

 lateral spine on each side; sixth abdominal somite with an anterior 

 median dorsal broad plate and a posterior pair of blunt spines, and a 



median dorsal spine on the posterior margin sculpta (p. 208) 



c *. Fourth and fifth abdominal somites without dorsal median spines; sixth 

 abdominal somite with an anterior dorsal triangular plate and a pos- 

 terior area of peculiar sculpture, and a median posterior dorsal mar- 

 ginal spine costata (p. 208) 



c '. None of abdominal somites with posterior dorsal medial spines or with 



sculpture stelleri (p. 210) 



b 2 . Thoracic and abdominal somites smooth, without grooves. 



c 1 . Eyes normal. Telson linguiform dybowskii (p. 213) 



c 2 . Eyes elongate. 



d 1 . Eyes 3%:1, no labral spine, one spine on inner margin of the inner 



uropod macropsis (p. 215) 



d 2 . Eyes 23^:1, labral spine present, no spines on inner uropod. 



pseudomacropsis (p. 217) 



