A. M. Taylor 275 



(a) the failure to get it to produce the characteristic symptoms 

 of attack on the strawberry plant; 



(6) the totally different character of the spicules; 



(c) the absence of sudden reduction in diameter behind the cloaca ; 



(d) large size of the spear; 



(e) the restricted extension forwards of the testis — which in 

 A. fragariae reaches to the anterior third of the length of the body 

 and in the black currant species does not extend beyond the middle ; 



(/) the swollen lips of the truncated end. 



The reasons against identification with A. ormerodis are 



{a) the failure to infect the strawberry plant ^\^th this species; 



(6) the larger size of the black currant species — 92 mm. as against 

 •65 mm. for large specimens in each case ; 



(c) the difference in the character of the spicules, though this 

 may be more apparent than real {v. above) ; 



{d) the presence of the narrow pharyngeal region (oesophagus) 

 between the bulb and true intestine; 



(e) the restricted extension forwards of the testis ; 



(/) the swollen "lips" of the truncated anterior end. 



Although the black currant worm may be said to jiossess characters 

 which belong to both the genus Aphelenchus and Tylenchus, yet it has 

 more in common with the latter group than the former. Especially is 

 this the case if the thin ridges alongside the cloaca can be interpreted 

 as a bursa. 



It is therefore considered advisable, until further work has been 

 done on these groups, to include the worm in question in the genus 

 Tylenchus with the specific name of ribes. 



DESCRIPTION OF PLATE III. 



Male. Fig. 2. Female. 



Mouth parts enlarged. ,, 4. Anterior opening. 



Portion of reproductive organs of $. 



Portion of reproductive organs of ^. 



Spicule of (J from side. 



Spicule of cJ (higher magnification shewing complete spicule). 



Cloaca of ^ (spicule omitted). 



Terminal papillae of (J. 

 Al.c. alimentary canal; calx, cavity of alimentary canal; h.c. body cavity; h.w. 

 body wall ; cl. cloaca ; f.c. follicle cell ; f.w. follicle wall ; n. nucleus ; n.h.w. nucleus of body 

 wall ; ooc. oocyte ; oog. oogonia ; ov. ovary ; ovd. oviduct ; o.ovd. opening of oviduct ; 

 ph. muscular pharynx ; pp. papillae; p.spq. primary spermatogonia; r.s. recoptacnlum 

 seminis ; sp. spine ; spc. spermatocyte ; spg. spermatogonium ; spt. spermatid ; spl. 

 spicule ; sp.m. special muscle ; spz. spermatozoa ; v.d. vas deferens ; iv.ph. wall of pharynx. 



{Received August 2Uh, 1916.) 



