26 



Perry C. Holt and Ann M. Weigl 





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Fig. 2. Scanning electron micrograph of a portion of the body of X. bashaviae. 

 Note ciliary tufts. 



length, 3.4 mm (3.4-4.2 mm); greatest diameter, 0.8 mm (0.6-1. 2mm); head 

 length, 0.7 mm (0.6-0.8 mm); head diameter, 0.5 mm (0.4-0.6 mm); diameter, 

 segment I, 0.4 mm (0.3-0.5 mm); diameter, sucker, 0.5 mm (0.4-0.5 mm). In 

 the holotype and one paratype, segment V was greater in diameter than 

 segment VII. The latter, which bears the ovaries and developing eggs, is 

 normally greater in diameter among all members of the order. In these 

 two specimens there are no large eggs. 



Scanning and transmission electron microscopy of X. bashaviae have 

 revealed the presence on the outer epithelium of numerous bristle-like 

 structures, each composed of a tuft of cilia. The tufts are most abundant in 

 the region of the mouth, but are also found on other parts of the head as 

 well as on the body segments (Fig. 2). They are not visible by light 

 microscopy, though "sensory" hairs have been detected in the mouth 

 region of other branchiobdellids (Franzen 1963:370; Moore 1895:499; 

 Holt, unpub. observ.). 



The animals widen uniformly from segment I to their greatest diameter 

 in segments VI and VII and from there become narrower towards the 

 sucker and are uniformly, but not excessively, flattened, except for the 

 terete head. The posterior annulus of each segment is only slightly less in 



