228 BULLETIX 120, UNITED STATES NATIONAL MUSEUM. 



eiulospherules in this region. The nuclei are very large, some of 

 the largest even slightly surpassing in size the smallest nuclei known 

 in the Protoopalinas. All of the nuclei show one or more large 

 clumps of massive chromatin under the nuclear membrane. The 

 nuclei seen in mitosis are obser\'ed to be shorter and broader than 

 the nuclei from the form truncata in a similar stage of mitosis. 



One would naturally assign this Opalina to a distinct species, but 

 there are found intermediate forms from the same species of host 

 and even in the same infection, grading over into the ordinary 

 O. ranamni: It seems necessary to assign them all to the same 

 species, treating them as O. ranarutn form cinctoidea. The name 

 oinctoidea is given to this fomia because of its resemblance to 

 Opallna chief a found by Collin in Bufo hufo [^B. vulgaris']. We 

 will discuss Collin's species later. If Collin's species should prove 

 to be merely a form of O. ranarum., as is possible, the cinctoidea form 

 Avould be transitional between the form cincta and the species type. 



OPALINA RANARUM. form PARVIPALMATAE, new forma. 



7'ype.— United States National Museum Cat. No. 1659G. 



Host. — Rana teiwporaria farvi'palmata Sevane, two infections, the 

 type infection from United States National Museum frog No. 38-487, 

 35 mm. long, from Ariege, France, Thomas and Miller collectors; 

 and another similar infection from United States National Museum 

 frog No. 38485, 80 mm. long, a female with eggs, from Parte, France, 

 collected August 31, 1906, by Thomas and Miller. 



Measurements of a characteristic individual. — Length of body 

 0.384 mm. ; width of body 0.19 mm. ; thickness of body, anterior end, 

 thick edge 0.042 mm., thin edge 0.038 mm., middle of body 0.04 mm., 

 posterior end 0.03 mm., diameter of nucleus 0.0053 mm. to 0.0085 

 mm.; diameter of endospherule 0.00225 mm. to 0.0025 mm.; cilia line 

 interval, anterior 0.0019 mm., middle 0.00287 mm., posterior 0.0038 

 mm. 



These infections show individuals rather similar to 0. ranariiin 

 . form truncata.^ but they are narrowly or broadly rounded behind 

 instead of broadly truncate. In the individual drawn, as in many 

 others, some of the nuclei seem to have disappeared; some large 

 nuclei are in a reticulate candition, others are in mitosis, and there 

 are many smaller nuclei, evidently daughter nuclei in different stages 

 of growth. It seems, therefore, that nuclear division is taking place 

 extensively in these large Opalinas, although one of the hosts was 

 taken the last of August and the other probably was collected at 

 about the same time ; and so their Opalinids are not in the midst of 

 the period of rapid division in the spring preceding the sexual phase 

 of the life cycle. The condition of these animals again emphasizes 



