PROCEEDINGS OF THE NATIONAL MUSEUM 



copepods 



number of ovisacs 



sez of ostracod length of number number of 



host station female of males copepodids spherical pyriform copepodid 



9 2906 . 47 



9 5 



9 3 



9 " .25 



9 " .42 



9 2 3 



cf " .33 



juv. & Coll. 4 . 23 b 



* Ostracod eggs present. 

 •> Spermatophore attached. 



Incidence of parasitism. — In spite of the similarity in size, the 

 female Sphaeronellopsis and her ovisacs are readily distinguishable 

 from ostracod eggs thru the valves of undissected preserved speci- 

 mens. The female Sphaeronellopsis has a characteristic yellow 

 color, and her ovisacs are less uniform in appearance than ostracod 

 eggs. The smaller and more transparent copepodids are more difficult 

 to see altho some were visible in intact ostracods. No male copepods 

 were discovered in undissected ostracods. 



Specimens appearing to have parasites were examined after being 

 cleared in glycerine to be rendered more visible. To increase the 

 reliability of the search, additional ostracods in which copepods had 

 not been seen in the preliminary examination were also examined 

 in glycerine, but this supplementary examination revealed very few 

 additional parasites. In all, 86 ostracods were examined in glycerine, 

 and in about half of these the shell was removed. 



Of the 407 ostracod specimens, including juveniles and adults, 25, 

 or nearly 1 out of 16, were found to be parasitized. Since juveniles 

 normally are not parasitized (all of the 95 juveniles from station 276 

 were free of copepod parasites), the degree of infestation of adults 

 is more significant biologically. Our most reliable data is from the 

 station 2906 collection of 170 ostracods, which includes about 141 

 adult females (15 with marsupial eggs), 6 adult males, and 23 juveniles. 

 Ten of the females and 1 of the males were parasitized, i.e., about 1 

 out of 13 adults. The success of the parasitism is evident when it is 

 considered that the copepod eggs being brooded by the ostracods 

 outnumber their own eggs. A female Parasterope seldom has more 

 than 13 eggs in her marsupium, less than the number in 1 copepod 

 ovisac. 



Host specificity.' — Sphaeronellopsis monothrix has been found 

 only in Parasterope pollex. One other myodocopid ostracod, Sarsiella 

 zostericola, is abundant in Hadley Harbor; 17 specimens, including 

 8 adult females, 1 adult male, and 8 juveniles have been examined 

 for sphaeronellids with negative results. It is noteworthy that in 



