74 University of California Publications in Zoologij [Vol. 16 



data at the present time would seem to iBdicate. Until this has been 

 done they may each be ranked as distinct species. One of these forms. 

 Hexamitus ovatus sp. nov., is considered in the following pages, to- 

 gether with H. intestinalis Dnj. and H. hatrnchorum sp. nov. 



These investigations were begun at the suggestion of Professor 

 C. A. Kofoid, whose help and encouragement have been unfailing 

 throughout the course of the work. 



Hexamitus ovatus sp. nov. 

 This flagellate has been found in aliuudance in tmly one host. Dic- 

 myctulus torosHs, occurring only sparingly in the other amphibians 

 examined. 



Morphology 



The form of this flagellate is ellipsoidal to ovoidal. with the broader 

 end anterior and 6 to 8/x in length. The posterior end may be slightly 

 pointed, but generally it is more or le.ss rounded. At the anterior 

 end is a mass of chromatin, the blepharoplast complex, which consists 

 of two granules (pi. 9, fig. 1), closely packed together .so as to appear 

 as one in most eases. From these arise the six anterior flagella. three 

 from each granule. The flagella are usually from 1.5-2 times the 

 length of the body, but are frequently much longer. 



Arising from the blepharoplast. one from each granule, and ex- 

 tending backwards through the cytopla.sm to the posterior end of the 

 body in a curve parallel to and rather near the periphery, are two 

 slender axostyles, so narrow as to appear at times as scarcely more 

 than a line. Arising from the distal ends of these are two trailing 

 posterior flagella. The axostyles are very flexible and often appear 

 twisted owing to the movements of the body (pi. 9, fig. 2). 



The nuclei are two in number and are situated immediately behind 

 the blepharoplasts, each being connected with a single granule of the 

 blepharoplast complex. The nuclei are elongated, rounded at both 

 ends and about 1.5 by 2 or 'B/x in size (pi. 9, fig. 1). 



The chromatin consists of one large, elongated, centrally located 

 mass, apparently continuous at the anterior end with the blepharoplast. 

 This chromatin ma.ss is often curved or club-shaped and is nearly as 

 long as the nucleus. A very definite nuclear membrane is present 

 which, especially prior to division, usually takes a heavy stain with 

 iron haeniatoxylin (pi. 9. fig. 1). 



