A REVIEW OF THE MYSIDACEA 17 



I cannot place L. erythraeus Colosi and L. affinis Colosi in this key. 

 L. erythraeus is very closely allied to L. typicus but, according to 

 Colosi, differs in the degree to which the rostral plate covers the 

 antennular peduncle and in trivial differences in the spinulation of 

 the telson. L. affinis is very similar to L. intermedins but differs in 

 that the rostral plate covers a larger area of the eye and in the slightly 

 different shape of the antennal scale. 



On the basis of the key I can place all but one of the specimens in 

 the collection. This odd specimen I have not named, preferring to 

 await further material before deciding whether the characters noted 

 are constant. 



LOPHOGASTER TYPICUS M. Sars 



Lophogaster typicus M. Sars, 1S57, p. 160. 



Occurrence. — Ireland ; identified by A. M. Norman*. 



LOPHOGASTER HAWAIENSIS Fage 



Data for this species will be found on page 242. 



LOPHOGASTER AMERICANUS, new species 



Figure 1, a 



Lophogaster typicus Ortmann, 1906, p. 23 (west Atlantic specimens). — Tat- 



tersall, 1926, p. 6. 

 Lophogaster sp. Smith, 1881, p. 445 ; 1884, p. 55.— Verrill, 1885, pp. 556, 558. 



Description. — Carapace not tuberculose but very minutely spinulose, 

 particularly on the anterior dorsal region and on the rostral plate; 

 rostral plate with the median process longer than the lateral and ex- 

 tending forward as far as the distal end of the antennular peduncle ; 

 posterolateral angle of the carapace produced into a short spine ; an- 

 tennal scale (fig. 1, a) of the "rotundate" type, the proportion of 

 length to breadth 10 : 6 ; 6 to 7 teeth on the outer margin in addition 

 to the terminal spine ; telson with 6 spines on the lateral margins in- 

 cluding the spines at the apex. 



Type. — A male, U.S.N.M. No. 81252, from the east coast of the 

 United States, Fish Hawk station 870, latitude 40°2'36" N., longitude 

 70°22 , 5S" W. 



Occurrence. — East coast of the United States : Fisk Hawk sta- 

 tions 870, 1 male, damaged, but about 20 mm., type ; 7282*, Gulf Stream 

 off Key West, Fla., latitude 24°21'15" N., longitude 81°52'15" W., 

 109 fathoms, February 19, 1902 ; 7283*, Gulf Stream off Key West, 

 Fla., latitude 24°17'30" N., longitude 81°53'30" W., 127 fathoms, 

 February 19, 1902; 7286*, Gulf Stream off Key West, Fla., latitude 

 24°18'00" N., longitude 81°47'45" W., 133 fathoms, February 19, 



