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SCOTTISH HAIRWORMS 139 



II. Key to Characters of Hairworms (Gordhd/E) 



RECORDED FROM THE BRITISH ISLES. 



'a. Body with scattered whitish dots ; surface (cuticle) under 

 high magnification smooth, without tubercles or faceted 

 pattern ; in male, strong ledge of cuticle behind cloacal 

 opening (Fig. 6) . . . . . Gordius (G, villoti) 



/'. Body without dots ; surface (cuticle) under high magni- 

 fication with faceted pattern or tubercles ; in male, no 

 ledge of cuticle behind cloacal opening (Fig. 7) . Parachordodes, 2 



a. Surface pattern simple, confined to one type of areole 

 (Figs. I and 3) . , . . . . 3 



b. Surface pattern compounded of two types of areoles 

 (Fig. 2) ...... . 4 • 



a. Surface pattern consisting of parallel, slightly waved lines 

 of tubercles running along the length of the body 

 (Fig. i) . . . . . . Pai-achordodes pleskei 



h. Surface pattern consisting of close-set, five- or six-sided 

 facets, bounded by refringent spaces in which are minute 

 inter-areolar tubercles (Fig. 3) . . . Parachordodes violaceus 



c. Surface pattern consisting of numerous tubercles set 

 round irregularly oval or roundish clear spaces ; pos- 

 terior end strongly grooved, but not bifurcated . Parachordodes tolosanus 



(female specimen). 



Explanation of Figures. 



1. Lined Hairworm — Parachordodes pleskei^ Ollaberry, Shetland. Surface pattern 



viewed in plan x 480. t. Tubercles ; /;•, faintly refringent prolongations 

 between lines of tubercles, probably indicating base of aieole ; a;-, clear 

 space of areole. The fine crossing lines represent the fibrillar mesh beneath 

 the cuticle. 



2. Large-spot Hairworm — Parachordodes tolosanus. Surface pattern viewed in 



plan X 480. /, Tubercles ; ar.i., smaller, clear type of areole ; ar.2, larger, 

 dark type of areole. The fine crossing lines represent the fibrillar mesh 

 beneath the cuticle. 



3. Faceted Hairworm — Parachordodes violaceus. Surface pattern viewed in plan x 



480. pa. Mound-like papillae, the form assumed by the central spaces in 

 the areoles. ?./., Inter-areolar tubercles, set in a clear space which borders 

 the areole. 



4. Faceted Hairworm — Parachordodes violaceus. Surface pattern viewed from the 



side X 480. Lettering as in Fig. 3. 



5. Large-spot Hairworm — Parachordodes tolosanus. Lateral view of the spines 



which occur on tubercles, showing body, bulbous base, and neck for attach- 

 ment, also two spines in situ x 800. 



6. Mottled Y{a.\x\\orn\^Gordius villoti, Whitadder, Berwickshire. Hinder end of 



male specimen x 50. c/, Cloacal opening ; /, post-cloacal ledge of cuticle ; 

 /, rows of minute tubercles or bristles ; lir, one of the branches of forked end. 



7. Faceted Y{?L\rviorm— Parachordodes violaceus. Hinder end of male specimen 



X 50. ;■//, Pre-cloacal rows of small tubercles, hairs or bristles, converging 

 at an angle ; cl, cloacal opening ; /, post-cloacal tubercles ; br, one of the 

 branches of forked end. 



