No. 2194. NORTH AMERICAN PARASITIC COl'EPODH—WlLiiON. 113 



4, Neck 2 times as lonj? as trunk; abdomen half the lenj^th of genital se^'nient; 

 Q'^'i strintrs half the length of whole body ; head Ilattened, nuith wider than 

 long (200 to 320 mm.) balaenopterac Korea and Dnnlelsseii, 1877. 



4. Neck and trunk the sam» length ; abdomen two-fifths length of genital seg- 

 ment; egg strings twice the length of whole body; head flattened, nmch 

 wider than long (140 mm.) tridentata Listow.sky, 1893. 



4. I.'eck 2 to 3 times as long as trunk; abdomen three-fifths length of genital 



segment; head cup-shaped anteriorly (90 to 125 mm.) 



crassicornis Steen.strup and lAltken, ISGl. 



5. Horns chitinous, at right angles to head, and both in the same straight line; 



abdomen half the length of genital segment ; egg strings no longer than 



abdomen (90 to 100 mm.) hisfiophori Thomson, 1889. 



5. Horns fleshy and very short, terminating in a small red knob ; abdomen half 

 the length of genital segment ; egg strings much longer than whole body 

 (100 mm.) piistiilosa Angas, 1847. 



5. Hums chitinous, slender, and scarcely projecting beyond the margins of the 



head ; abdomen stout and less than half the length of genital segment ; egg 

 strings twice the length of whole body (150 to 200 mm.) 



filosa (Linnaeus), 1758. p. 119. 



6. Head squarely truncated anteriorly, with concave sides; horns parallel with 



the neck ; neclv and trunk the same length ; abdomen half the length of 

 genital segment (225 mm.) instriicta, new species, p. 122. 



6. Head cup-shaped anteriorly, with convex sides; horns extending diagonally 

 outward ; neck one-fifth shorter than trunk ; abdomen a third the length 

 of genital segment (ISO mm.) ortlwgorisci Vv'right, 1870, p. 124. 



6. Head shaped like a clove, largest anteriorly ; horns parallel with neck ; neck 

 3 times as long as trunk; abdomen half as long as the genital segment 

 (275 mm.) charcoti Quidor, 1912. 



PENNELLA SAGITTA (Linnaeus). 



Pcnnatnla sayitta Linnaeus, Systema Naturae, 1758, p. 819, pi. 3, fig. 13. — 



Ellis, Philos. Trans., vol. 53, 17G3, p. 419, pi. 1. — Cuvier. Ilegne Animal, 



vol. 4, 1817, p. 36. — Dekay, Amer. Journ. Science, vol. 4, 1822, p. 87, 1 



text fig. 

 Lerncopcnna sagitta Blain\^ij.e, Jouru. de Physique, vol. 95, 1822, p. 379, 



pi. 1, fig. 5. 

 Lerncopcnna brachiata Blainville, Journ. de Physique, vol. 95, 1822, p. 



44G, pi. 1, fig. 4. 

 Pcnnatula hocconii LAMABTiNifeKE, Atlas du Voyage de la Pdrouse, 1798, 



pi. 20, fig. G. 

 Lcrnaea diodontis Oken, [iehrbuch Naturgeschlchte, 1816, p. 184. 

 PcnncUa sagitta Nordmann, Mikrographische Beitriige, 1832, p. 121, pL 



10, figs. G-8. — Steexstrup and Lutken, Kong. Danske Videns. Skrifter, 



1S61, p. 409, pi. 14. fig. 31. 

 PcnncUa diodontis Oken Lehrbuch Naturgeschlchte, 1816, p. 358. 

 PcnncUa diodontis Oken, Chamisso, and Etsenhardt, Nova Acta Acad. 



Caes. Bonn, vol. 10. 1821, p. 350, pi. 24. fig. 3. 

 PcnncUa diodontis Quidor, Deuxi&me Expedition Antarctlque, Charcot, 



1912. p. 205, pi. 1, fig. 2; pi. 2, figs. 19-22: pi. 4. fig. 38. 



Remarks. — As the above synonomy shows, various authors have 

 attempted to establish 4 or 5 different species upon the material 

 obtained from the genus Diodon. Linnaeus made the mistake of 

 77403— Proc.N.JL vol.53— 17 8 



