THE OPALINID CILIATE INFUSORIANS. 63 



are alwaj'S so connected, except in dividing cells. The eight (?) 

 chromatin masses probably indicate four as the true macrochromo- 

 some number, for in nuclei in the anaphase stage (fig. 36, c) there 

 are two groups of four (?) macrochromosomes each in each elongated 

 nucleus. It is, however, unsafe to accept definitely counts of chro- 

 mosomes in nuclei whose preservation is as poor as in these speci- 

 mens, which were preserved in formalin. 



PROTOOPAUNA SATURNAUS (Leger and Dnboscq). 



Opalina saturnalis Leger and Duroscq (1904). 



Specimens have been deposited with the United States National 

 Museum, being Cat. No. 16459. 



Host. — The marine fish Box hoops Linnaeus, from the Mediter- 

 ranean Sea. This is the only non-Amphibian species known to con- 

 tain Opalinids. 



Protoopalina saturnalu was discovered and carefully described by 

 Leger and Duboscq in 1904. Several of their excellent figures are 

 here copied. As I have had only moderately well preserved material, 

 and no living animals, for study, the description here given is taken 

 mostly from Leger and Duboscq's much fuller description. 



Measurements of an average individual of the elongated form, from 

 my material. — Length of body 0.152 mm. (Leger and Duboscq report 

 individuals up to 0.25 mm. in length) ; width of body 0.022 mm. ; 

 length of posterior " spine " 0.00833 mm. to 0.019 mm. ; length of an- 

 terior cilia 0.02 mm. to 0.025 mm. ; length of restin'g nucleus 0.0112 

 mm. ; width of resting nucleus 0.0092 mm. ; length of endospherules 

 0.008 mm. ; width of endospherules 0.0033 mm. ; cilia line interval, 

 anterior 0.0022 mm., posterior 0.0052 mm. 



Measurements of an ordinary individual of the ovoid form, after 

 Leger and Duboscq. — Length of body 0.1 mm. ; width of body 0.06 

 mm. ; length of posterior spine 0.005 mm. ; length of anterior cilia 

 0.01 mm. (from Leger and Duboscq's text-figure 3) ; diameter of rest- 

 ing nucleus 0.0108 mm.; length of anaphase nucleus 0.0233 mm.; 

 width of anaphase nucleus 0.00833 mm. 



All the Box hoops at Cavaliere and Cannes are said to be infected, 

 the intestine and the rectum showing very numerous P. saturnalis. 

 At Banyuls three out of five of the young Box hoops contain the 

 Opalinids. Box salpa Linnaeus, which lives in the same regions, never 

 contains the Opalinids. 



Protoopalina saturnalis is pale yellow, the color being due to the 

 presence in the ectosarc alveoles of a substance which looks like, but 

 is not in reality, oil. [Many species of Opalinids have a similar yel- 

 low color from the same cause. See Metcalf (1909).] This species, 

 like Protoopalina caudata, P. orientalis, Cepedea dimidiata, and some 



