702 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxi. 



Furthermore the sexual organs shown in the genital segments of 

 Thomson's ''two" sexes are exactly alike, which would be rather an 

 anomaly among the Caligida?. 



The male of GJoiojwte.s Jn/gomianus was described by Stel)bing in 

 1900, and is exactly what would be expected in a genus the females of 

 which show such manifest beginnings of degeneration. 



But this male is altogether different from that described by Thom- 

 son and adds to the probability that the latter is really an undeveloped 

 female. 



This species is founded upon two excellently preserved adult females 

 which were obtained from the outside surface of a swordtish at Woods 

 Hole, Massachusetts. (Cat. No. 6209, U.S.N.M.) 



Genus ALEBION Kroyer. 



The genus Alebion was established by Kroyer in 1863 for a single 

 specimen which he claimed was a male and to which he gave the spe- 

 cific name earvhariad from its host. 



This was sufficiently different from Caligus on the one hand and 

 from Pandarus on the other to warrant its separation as an interme- 

 diate form, and for it Kroyer gave the following diagnosis: 



Proboscis intermediate in form between that of the Cahgin;e and the Pandarinae. 

 Palps (second maxillae) large and stout. Feet of the third (the first thoracic) pair 

 two-branched, the branches Inarticulate, the inner one being the smaller. The first, 

 second, and third pairs of thoracic feet armed with corneous bodies of a peculiar 

 form on the laminpe of their outer branches. Fourth thoracic legs very rudimentary, 

 uniramose, and two-jointed. Two teeth projecting from the posterior border of the 

 carapace. Sixth thoracic (genital) segment fringed with setae. Antennal palps, 

 anterior subsidiary hooks (first maxillae), lunules and furcula lacking." 



In 1892 van Beneden described'' the male and female of a species 

 which he claimed to be the type of a new genus, CaJigera dlfficilis. 

 His figures and descriptions are both inaccurate and incomplete, but 

 enough was- given to show plainh" that he had secured a species of 

 Alebion^ and it was rightly transferred to that genus by Bassett Smith 

 in 1899. 



Bassett-Smith himself found in 1898 what he claimed to be the 

 female of Kroyer's species and gave in the following year these genus 

 characters: 



Carapace large, oval. Frontal plates well marked. Anterior antennae two-jointed. 

 Fourth thoracic segment with small dorsal plates. Genital segment broad, prolonged 

 backward in two elongate processes with the ends and outer margins dentate. 

 Abdomen biarticulate. Caudal plates with long setae. The first three pairs of thor- 

 acic limbs biramose, with lunate corneous bodies on the outer branches; fourth pair 

 of limbs quite rudimentary, hidden. <^ 



« Bidrag til Kundskab om Snyltekrebsene, 1863, p. 168. 



^ Quelques nouveaux Caligides de la Cote d'Afrique, et de TArcliipel des Azores, 

 1892, p. 258. Plate iv. See also p. 367. 



<^ A Systematic Description of Parasitic Copepoda found on Fishes, with an p]nu- 

 meration of the known species, 1899, p. 462. 



