566 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 55. 



lateral processes on the cephalotliorax, in the long slender neck, and 

 in the posterior processes on the abdomen. The males differ in the 

 entire absence of swimming legs, in the fusion of the basal joints 

 of the maxillipeds, and in the structure of the antennae and mouth 

 parts. The family is thus clearly differentiated from all the other 

 copepod families and occupies a place peculiarly its own, its males 

 closely resembling those of the Lernaeopodidae and its females bear- 

 ing some external resemblance to those of the Lernaeidae. 



ARTIFICIAL KEY TO THE GENERA. 



1. Posterior processes cylindrical, smooth, and divided into large lobes; neck 

 bent and twisted and armed witli numerous cliitin horns. 



Pertplexis, new genus, p. 598. 



1. Posterior processes cylindrical, smooth, neither lobed nor divided; neck 

 straight and smooth, no chitin horns 2. 



1. Posterior processes covered with gill cones or cylinders; neck straight and 



smooth, with horns or processes 3. 



2. Cephalothorax orbicular, without processes; neck stout and flattened. 



Opimia Wilson, 1908, p. 589. 

 2. Cephalothorax transversely ellipsoidal, with three pairs of prominent pro- 

 cesses ; neck slender and cylindrical Paeon, new genus, p. 590. 



2. Cephalothorax orbicular, furnished with cartilaginous horns; neck slender 



and cylindrical Trypaphylum Richiardi, 1878, p. 588. 



S. Cephalothorax a narrow cylinder, with small lateral processes or horns ; neck 



filose Rebelula Poche, 1905, p. 576. 



8. Cephalothorax short and very wide, much flattened, with enormous lateral 

 processes, often lobed ; neck thick and stout— Sphyrion Cuvier, 1839, p. 566. 



Genus SPHYRION Cuvier. 



Chondracanthiis Quoy and Gaimabd, Freycinet's Voyage autour du Monde, 1824, 



Zoologie, Atlas, pi. 86, fig. 10. " Chondracanthe lisse." 

 Sphyrion Cm'iER, Le R&gne Animal, 1830, vol. 3, p. 257. " Sphyrion lisse." 

 Sphyrion GufiRiN-MENEviLLE, Iconographie du RSgne Animal, 1829-1843, vol. 2, 



p. 11, pi. 9, fig. 4. Sphyrion laevigatus. 

 Sphyrion Milne Edwards, Histoire Naturelle des Crustacgs, 1840, vol. 3, p. 525. 

 Lestes Kk0yer, Danmarks Fiske, 1845, vol. 2, p. 517. 

 Sphyrion Steenstrttp and LiJTKEN, Kong. Danske Videns. Selskab. Skrifter, 



1801, ser. 5, vol. 5, pp. 847 and 432. 

 Lesteira Kb0yee, Naturhistorisk Tidsskrift, 1863. ser. 3, vol. 2, p. 402. 

 Lesteira Helleb, Reise der Novara, 1865, Crustacea, p. 228. 

 Lesteira G. M. Thomson, Trans. New Zealand Inst., 1890, vol. 22, p. 370. 

 Sphyrion Bassett-Smith, Proc. Zool. Soc. London, 1899, pp. 441 and 488. 

 Sphyrion Stebbing, Cape of Good Hope, Dept. Agric, South African Crustacea, 



Sphyrion laerigatum, p. 60, pi. 4, 1900. 

 Sphyrion Thoe, Ann. Sci. Nat, ser. 8, 1900, vol. 11, p. 277. Sphyrion austraU- 



CMS, new species, p. 280. 

 Sphyrion Quidob, Archiv. Zool. exper. et gen., ser. 5, 1912, vol. 10, p. xxxix, 



Sphyrion delagci, new species, p. xii ; stewarti, new species, p. xiii. 

 Sphyrion T. and A. Scott, British Parisitic Copedoda, 1913, vol. 1, p. 164. 



External generic characters of female. — Cephalothorax trans- 

 versely expanded into a pair of enormous soft processes of varying 



