Sept. 15, 1915 Tylenchus Similis 563 



out that the males and females were so unlike that, had they not been 

 found in conjunction and under such circumstances as to preclude the 

 possibility of error in assigning them to one and the same species, it 

 is probable that they would have been considered to be separate species- 

 The remarkable similarity of the male to those of the species of Tylen- 

 chus previously found about banana roots in Fiji did not escape notice, 

 but as the Fijian observations were incomplete, no females of the Fijian 

 species having been seen, the question of the identity of Tylenchus 

 similis and Tylenchus biformis was not raised. The present investiga- 

 tion establishes the identity of these two species. The species should 

 therefore bear the prior name "Tylenchus similis Cobb, 1892." 



This nematode is, in the opinion of the writer, clearly proved to be the 

 primary cause of a disease of the sugar cane. Mr. S. F. Ashby, in a 

 recent letter, writes as follows concerning its relation to banana: 



I at first attributed the attack [on banana] to the joint action of a Fusarium and a 

 coli-like bacterium frequently isolated from the rot; inoculation of either or both failed 

 to cause a similar rot. Eelworms * were always found present, and on going through 

 samples from various sources again I invariably came across the same species in the 

 advance margin of the rot both in rhizomes and roots. 



The specimens forwarded by Mr. Ashby contained no other organism 

 that would appear to have caused the lesions. 



The following . description of Tylenchus similis is derived from speci- 

 mens forwarded from Jamaica by Mr. Ashby in diseased banana tissues. 

 Tylenchus similis Cobb, r ^ 3.^ IL5_J_: j:59^« 88^ 7 ^^ /pj^^ 



Tylenchus biformis Cohh, igoT. V 2.5 3_^ / 3.4 3.8 2.6 



moderately thick layers of the transparent, naked, colorless cuticle 

 are traversed by somewhat more than 400 transverse striae, which are 

 not further resolvable. The transverse striae are interrupted on the 

 lateral fields by conspicuous wings, the presence of which is indic&.ted 

 by four longitudinal striae taking up a space equal to one-fourth to 

 one-third the diameter of the body. The two outer of these lines 

 are more conspicuous than the two inner, inasmuch as they are some- 

 what wider and more refractive. The two inner lines are sometimes 

 faint and occupy about one-fourth to one-fifth the width of the entire 

 wing space. The outer margins of the wings are almost imperceptibly 

 crenate, a feature which is associated with the transverse striae of the 

 cuticle; the inner lines are also crenate, but even less markedly so. 

 These wings begin opposite the base of the spear, where, however, they 

 are not so pronounced as along the median regions, and extend backward 

 to near the end of the tail. They maintain their maximum development 

 in a rather uniform way from opposite the nerve ring to a little behind 

 the anus. The posterior portion of the neck is subcylindroid, while the 

 anterior portion is convex-conoid, and ends in a rounded head, which in the 



' Nematodes. 



