610 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxiii. 



{occidentalism belonging to the Occident or Western Hemisphere, 

 the only other species being from the Indian Ocean and bearing the 

 name P. orientalis.) 



Nauplius. — Body an elongated ellipse, more than twice as long as 

 wide, with evenly rounded ends. Pigment a beautiful reddish pur- 

 ple, distributed in a large irregular eye spot at the anterior end, a 

 narrow line along either side halfway between the margin and the 

 mid line, and a row of irregular spots across the posterior end. 

 Balancers long and of the usual spathulate form, the cylindrical base 

 being fully two-fifths of the entire length. 



Total length, 0.4 mm.; width of body, 0.16 mm. 



This new species was found upon the inside of the operculum of 

 the cobia, Rachycentron canadus Linnaeus. They seem to prefer the 

 dorsal angle, four or five individuals being found there on either 

 side, huddled close together. In addition to the types recorded 

 above, a second lot, Cat. No. 32809, U. S. N. M., was obtained from 

 the gill cavity of the same fish. 



On being removed and placed in water they are found to be quite 

 active, swimming about freely, though not with the rapidity of 

 Caligus or LepeojMieirus. They have a very marked propensity 

 for coming to the surface of the water and lying there for hours at a 

 time. They seem to hold themselves in position by getting a little 

 air under the edges of the membranous wings and thus buoying 

 themselves up. These wings are so thin and pliable, however, that 

 they are constantly getting wrinkled and snarled up; and if left 

 for any time in an aquarium the chances are that the wings will 

 require considerable straightening before preservation. 



Tins is the first species that has been obtained since Steenstrup 

 and Llitken founded the genus in 1861. They did not succeed in 

 finding any males, and a most careful search for them in the present 

 instance was also without success. 



There are now two clearly defined species of this genus, each of 

 which is represented by females only. 



Heller (1865) and Bassett-Smith (1899) noted the genus, but the 

 account which each of them gives is evidently taken directly from 

 the original description without the examination of any specimens. 



The discovery of a second species would ordinarily modify the 

 original genus diagnosis somewhat, but in the present instance it 

 makes such radical changes that only a little of the original is left. 



Steenstrup and Liitken evidently had a limited supply of spec- 

 imens, all of which had been preserved in the East Indies and sent 

 home. 



They therefore content themselves with a genus diagnosis of two 

 lines and a half, and a species description of only ten lines in length. 

 Their diagnosis simply states that this genus differs from Caligus 



