XIPHOSURA 



By Joel W. Hedgpeth, Scripps Institution of Oceanography, University of California 



The. occurrence of Limulus polyphemus on the 

 shores of the northern Gulf of Mexico is so limited 

 that few biologists realize that it occurs there at all. 

 To others, the statement of range given ia such 

 works as Ekman's Tiergeographie des Meeres, viz., 

 New England to Yucatan, implies widespread 

 occurrence in the Gulf of Mexico. Large popu- 

 lations of the horseshoe crab occur from Long 

 Island to about St. Petersburg, Florida. Al- 

 though Limulus is associated with ba.ys and 

 evidently requires estuarine conditions for opti- 

 mum populations, its occurrence along the north- 

 ern shores of the Gulf of Mexico is limited. It 

 appears to be common only in the northeast corner. 

 Gary (1906) reported an abundant population from 

 the Chandeleur Islands, and it may be from this 

 population that the sporadic records for Mis- 

 sissippi and Alabama result. According to 

 records from the Alabama Museum of Natural 

 History, Limulus was taken on Dauphin Island 

 in August 1939, and several individuals, both 

 males and females, were observed at night on 

 April 20, 1948, in the same locality. A large 

 male was taken at Wolf River, Baldwin County, 

 on May 13, 1948. A specimen was collected 

 from Santa Rosa Sound near Pensacola on 



February 20, 1938. The only trans-Mississippi 

 record for this animal is of a specimen collected 

 by C. T. Reed on Padre Island about 1940 or 

 1941. In view of the widespread occurrence of 

 many invertebrates on both the Middle Atlantic 

 and northern Gulf coasts this erratic distribution 

 of Limulus is a curious anomaly. For a recent 

 report on the natural history and breeding habits 

 of Limulus, see Sinister (1950). In regions where 

 the horseshoe crab is abundant, it may be a serious 

 predator on soft clam beds, and control measures 

 are being considered in Massachusetts. It is 

 reassuring, however, to learn that control measures 

 are considered costly and of doubtful efficacy as 

 it would be a pity to exterminate one of our 

 greatest zoological curiosities. 



LITERATURE CITED 



Gary, L. R. 



1906. \ contribution to the fauna of the coast of 

 Louisiana. Bull. Gulf Biologic Station 6: 50-59. 



Shuster, Carl X., Jr. 



1950. Observations on the natural history of the 

 American horseshoe crab, Limulus polyphemus. 

 Third Rept., Inv. methods improving shellfish 

 resources, Mass.: 18-23, 2 figs. 



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