MALARIA EXPEDITION TO NIGERIA 31 
The embryos are found in the peripheral and in the heart's blood. Its length 
in the fresh condition is 1 1 7 ^ breadth, 3 m- It has a very marked sheath which 
can often be seen trailing in front or behind the worm in the fresh specimen 
(plate XIII, fig. 3). The embryos move backwards or forwards with snaky move- 
ments, and also rush very energetically forwards and backwards inside their 
sheaths. The head end is rounded and has a six lipped prepuce through which a conical 
papilla can be observed to be protruded ; this bears at its apex a fine projecting spine. 
The papilla and its spine can be retracted within its sheath — an action very actively 
performed in fresh microscopical preparations. The body contents appear finely 
granular ; at the junction of the anterior and middle thirds is a highly retractile spot. 
The tail end tapers very slightly and ends bluntly rounded. In stained specimens 
(plate IV, fig. 4), the length of the embryo is 86 - o^ ; the length of the sheath 
beyond the worm proper both anteriorly and posteriorly varies enormously. The 
head end shews generally only a looseness in the arrangement of the small cells — 
sometimes a baying. 
Spots. — 1. A narrow transverse slit — fairly constant ; distance 2 8 - 6. 
2. A lateral rounded bay — not always present ; distance 40^7 . 
3. A clear band across the worm — constant ; distance 6tyi. 
4. A small lateral slit — only occasionally seen ; distance CjCro. 
Spots 2 and 4 are always on the same side of the worm. 
Filaria spiralis avium major. Nov. Sp. 
Definitive hosts : Hvphantornis. Sp. incert. 
Sitagra brach\ptera. 
Hyp ban torn is aurantius. 
Site. In Sitagra bracbyptera the adult worms were found in a thick walled 
cyst on the right leg situated deeply under the tendons on the bone. The cyst 
contained one small (male) and two large (female) worms. This bird also contained 
embryos and adults of F. spiralis. Although similar in appearance and site the 
two worms are quite distinct, the female of F. spiralis major being three or four 
times the length of the female of F. spiralis — and moreover they have different 
embryos, a fact conclusively demonstrated by the rupture of the uterus in each case 
and the examination of the contained embryos. 
The female, spiral in form, has nine turns. The spiral is right-handed. The 
total length is 17-3 mm., the central breadth 0-43 mm. 
Cobb's formula : 
— , — , — , 0-64 — 
Similarly to F. Spiralis, there is an anterior and posterior portion beyond the 
spiral, the anterior of which is the longer. The cuticle at the anterior end is thin, 
but thicker at the posterior end. Laterally the cuticle is thickened, and along the 
