430 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.59. 



CLAUSIDIUM CAUDATUM (Say}. 



Binoculus caudatus Say, Journ. Acad, Nat. Sci., Philadelphia, vol. 1, 1818, p. 437. 



Host and record of specimens. — This parasite was found in con- 

 siderable numbers on various parts of the body of Callianassa major 

 Say, dug from the sand of the bay shore of the St. John River in 

 Florida by Thomas Say. 



External specific characters of female. — Body subovate; cephalo- 

 thorax semioval or parabolic, posterior edge retuse for the reception 

 of the free thorax; anterior antennae horizontally extended, more 

 than half as long as the body, with short, rigid hairs. Basal seg- 

 ments of free thorax very short, transverse ; terminal segment longer, 

 semiorbicular, narrower than the preceding ones and concealing 

 the genital segment; abdomen and genital segment half as long as 

 the body, with three segments, the basal one (genital segment) 

 longitudinally quadrate, the second one transversely quadrate, the 

 third segment bifid and bisetous at the tip. Length, 0.82 mm. 



In nine-tenths of the specimens the two sexes were taken together, 

 the male clinging to the abdomen of the female so as to conceal by 

 his body the two terminal segments. 



Remarks.- — The above description is modified from the one given 

 by Say and somewhat condensed. The nomenclature has been 

 changed to agree with that now in use for the copepods, but other- 

 wise the statements are as Say gave them. They leave no doubt of 

 two things — first, that he was describing a species of Glausidium, 

 and second, that it differed from the other species in important par- 

 ticulars. In referring the species to its genus Say declared: "I have 

 placed this parasite in Geoffroy's genus Binoculus, not in consequence 

 of the particular definition of that genus, but from a general resem- 

 blance in the outline and similarity in the number and proportion 

 of the segments of the body, which it unquestionably bears, to the 

 singular animal discovered by that author, now the type of the 

 genus." This " singular animal" was the European Argulus foliaceus , 

 and it is very evident that Say was not dealing with anything belong- 

 ing to that genus. 



Accordingly we may transfer his species to the genus Glausidium 

 and retain its specific name until future research can furnish us the 

 details necessary to fully establish it. 



