100 BULLETIN 2 01, UNITED STATES NATIONAL MUSEUM 



Type lot. — U.S.N.M. No. 81257, numerous specimens, mostly imma- 

 ture, but one adult male, from Cape San Bias, Fla. 



Occurrence. — Gulf of Mexico : Cape San Bias, Fla., surface, elec- 

 tric light, March 7, 1885, numerous specimens, mostly immature, but 

 one adult male (type lot) . West coast of Panama : San Jose, Perlas 

 Island, Gulf of Panama, Dr. Th. Mortensen collector, January 27, 

 1916, 2 males, 1 female. 



Distribution. — The type specimens were collected off Cape San 

 Bias, Fla., in the Gulf of Mexico. I have examined specimens taken 

 by Dr. Th. Mortensen at San Jose, Perlas Islands, Gulf of Panama, 

 which I am unable to separate from those collected off Florida. I 

 cannot find any character by which they may be distinguished and 

 must refer them to this species. If my identification is correct G. mex- 

 icanus is known from both sides of the Isthmus of Panama. It is the 

 only mysid with such a distribution and is therefore of special interest. 

 It seems probable that the species has reached the Pacific coast of 

 Panama by migration through the Panama Canal and its probable 

 brackish water habits would facilitate such migration. 



Remarks. — This species is most closely related to G. johnsoni and 

 to G. dissimilis. In all three species the exopod of the third pair of 

 pleopods of the male is very stout and curiously modified, quite unlike 

 that of any other species of the genus. The three species may be 

 distinguished by the presence or absence of reflected lobes on the 

 carapace and by the presence or absence of a spine on the fifth abdomi- 

 nal somite. G. johnsoni and G. dissimilis have no reflected lobes on 

 the carapace, but in G. mexicanus reflected lobes are present on the 

 carapace. G. johnsoni and G. mexicanus have no spine on the fifth 

 abdominal somite, but G. dissimilis has a prominent spine on the 

 fifth abdominal somite. These species also differ slightly in the form 

 of the modified exopod of the third pleopods of the male. Otherwise 

 the species are very similar in most details of their structure. 



Genus ANCHIALINA Norman and Scott 



Anchialus Kr0yeb, 1861, p. 58. 

 Anchialina Noeman and Scott, 1906, p. 24. 



ANCHIALINA TYPICA (Kr^yer) 



Anchialus typicus Kb0yeb 1861, p. 53, pi. 2, fig. 7a-l. 



Anchialina typica Hansen, 1910, p. 52, pi. 7, fig. 2a-k. — Tattersall, 1936a, p. 96. 



Occurrence. — Atlantic Ocean : Key West, Fla., electric light, sur- 

 face, 1884, 1 male; Cape San Bias, electric light, surface, March 7, 

 1885, 32 males; John B. Henderson and Dr. Paul Bartsch collected 

 material at four Tomas Barrera Expedition to Cuba stations: Off 

 Santa Lucia, collection number 28, May 12, 1914, 6 males; Punta 



