112 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.53. 



could easily obtain such immature specimens while attached to some 

 larger fish which was the regular host of the parasite. 



At all events, with no data on the anterior two-thirds of the body, 

 including all of the appendages, the species can not be accepted. 



Pennella rubra Brian (1906, p. 86, pi. 7, fig. 3). This was a single 

 specimen, without egg strings and lacking all that part of the ante- 

 rior body which had been buried in the tissues of the host. This 

 lack of egg strings, as well as the condition of the plumose appen- 

 dages, show it to have been an immature stage of some species infest- 

 ing the sunfish on which it was found. Brian himself afterward 

 recognized this, and in 1912 (p. 16) placed the species as a synonym 

 under P. filosa. 



Pennella sultajia Nordman (1864, p. 485, pi. 5, figs. 12-16). This 

 species was first described briefly by Milne Edwards (1840, p. 523) 

 and ascribed to Nordmann in accordance with manuscript in the 

 Paris Museum. The manuscript was afterward published by Nord- 

 mann as above, but the species does not belong to the genus Pen- 

 nella., and in the following year was established by Heller (1865, 

 p. 251) as the type of the new genus Lernaeolophus. 



KEY TO THE SPECIES OF THE GENUS I'ENKELLA. 



1. Length 50 mm. or less, exclusive of the egg strings 2 



1. Length 100 mm. or more, exclusive of the egg strings 3 



2. Head spherical, the same width and length, covered with minute and regular 



excrescences ; two soft, slender horns, 2 to 3 times the length of the head, 

 pointed backward (10 to 20 mm.)' sagitta (Linnaeus), 1758, p, 113. 



2. Head much wider than long, flattened dorsoventrally, deep cut at the center, 

 covered with large irregular excrescences ; two slender horns a little longer 

 than the head and pointed backward (40 to 50 mm.) 



exocoeti (Hoi ten), 1802, p. 115. 



2. Head wider than long, flattened dorsoventrally, squarely truncated anteriorly, 

 not cut at the center, but covered with irregular excrescences ; three soft, 

 slender horns, the lateral ones at right angles to head and branched 

 (30 mm.) lioiiviUei Quidor, 1912, p. 116, 



2. Head much longer than wide, with wing-like excrescences on either side; 



two stout conical horns much shorter than head and at right angles to 

 it (15 to 25 mm.) varians Steenstrup and Liitken, 1S6L 



3. Three horns, long and slender, at right angles to head, the dorsal one 



shorter than the lateral ones; neck slender and much 'longer than 



trunk 4 



8. Two horns, short and blunt, at- right angles to head; neck shorter than 



the trunk and nearly of the same diameter 5 



8. Two horns, long and soft, pointed backwards ; neck thick and as long as 



the trunk or longer 6 



4. Neck 3 times as long as trunk; abdom.en two-fifths length of genital seg- 



ment; egg strings half the length of whole body; head minute and spheri- 

 cal (175 to 225 mm.) antarctica Quidor, 1912. p. 110. 



* Average total length of species. 



