1909.} | ‘THREAD-WORMS OF THE RED GROUSE. 349 
(iv.) Family Filariide. 
(v.) #reartA suiTHT Sambon. 
Dr. Sambon * has described a microfilaria or larval form of 
some species of Vilaria in the blood of grouse. The adult forms 
of such larve usually live in the lymphatics and subcutaneous 
tissues; their larvee pass into the blood and are conveyed to new 
hosts by some blood-sucking insects. 
I am greatly indebted to Dr. E. A. Wilson, net only for 
most of the figures which he has kindly drawn, but also for 
much help during the working out of the material upon which 
this paper 1s based. 
EXPLANATION OF THE PLATES. 
All the figures have been drawn by Dr. E. A. Wilson. Figures 1 to 27 inclusive 
refer to Trichostrongylus pergracilis, figures 28 to 40 inclusive to Tvichosoma 
longicolle. 
Prate XLVIII. 
Fig. 1. Male Trichostrongylus pergracilis, showing alimentary canal, spicules, 
and genital bursa. Magnified. 
2. Female 7. pergracilis, showing cesophagus, cephalic glands, ovary, uterus 
with segmenting eggs, ovejector, and vagina. Magnified. 
. Headend of thesame, Showing mouth, oral bulb, pharynx, and cesophagus, 
also the cuticular ridges. More highly magnified. 
. Tail end of the same. Magnified as fig. 3. Showing anus, rectum, rectal 
glands, and posterior loop of uterus. 
. Portion of cwsophagus of the same, showing arrangement of cells with 
large nuclei forming the cesophageal walls. More highly magnified. 
Pratt XLIX. 
. Head end of same, showing cephalic glands. Magnified. 
. Cuticle of same, one-third from anterior end, showing the ridges. Magnified, 
. Vagina and the two ovejectors lying i situ in one straight line, and the 
two outer ends of the uteri containing segmenting eggs. Magnified. 
. The ovejectors more highly magnified. The thread-worm has been crushed 
and the ovejectors have been pressed out and have come to lie parallel 
with one another. The lower ends of the uteri with their secreting 
eclumnar cells are seen, one of them contains a segmenting egg. 
10. Ventral view of posterior end of male, showing arrangement of ribs and of 
spicules. Highly magnified. 
— oD 
Or 
Fig. 
ie} GO NTS 
PuateE L. 
Fig. 11. Lateral view of the same, showing the spicules retracted. Highly 
magnified, 
12. The same, showing the spicules protruded and divaricated. Highly 
magnified, 
13. The same, seen ventro-laterally, showing attachment of muscles. 
14, Various views and stages of spermatozoa. 
Puate LI. 
Fig. 15. Unsegmented egg. 
16. Egg with two blastomeres. 
17, Ege with four blastomeres. 
18. Egg with eight blastomeres, only six showing. 
19. Egg with eight blastomeres, all showing. 
20. Ege with sixteen blastomeres. 
ea aS AE a oo A SEY ad ES 
* Jour. Trop. Med. and Hyg. x. 1907, p. 804. Filaria smithi cannot, however, 
stand, as the name is pre-occupied by Cobbold’s species Filaria smithit trom 
the Elephant, Tr. Linn. Soc. London, 2nd ser, 11, 1882, p. 237. 
