Terminal filaments, opercula, and niammillations have 

 been reported in this group. 



Terminal filaments have been observed in the genera 

 Tetrameres, Cystidicola, Metabronema, Ascaropliis, Rhab- 

 dochona, and Spitutectiis. They are not uniformly present, 

 however, in all species of the genera in which they occur. 

 The number of filaments, and their length, is variable 

 in some species while it is constant in others. 



The filaments of Tetrameres were described by Seurat 

 (1914) and Foster (1914). Seurat described an egg of 

 the flattened oxyurid type possessing a tuft of filaments 

 at each pole (Fig. 141E). He did not attempt an analysis 

 of the membranes of the egg envelope. Foster noted 

 similar filaments in a species of Tetrameres (Tropido- 

 cerca) from the American woodcock. He found seventeen 

 to twenty-three filaments forming the polar tufts. Most 

 of them were not over half the length of the egg, but 

 one or two at ea.h pole were twice as long (Fig. 141D). 

 Foster points out that these filaments are not prolonga- 

 tions of the chitinous shell but are added after the shell 

 is complete. He considers them analogous to the mam- 

 millations seen in the shell of Ascaris lumbricoides, a 

 view which is supported by our studies. Sandground 

 (1928) observed polar filaments on the eggs of Tetrameres 

 paucispina. 



Skinker (1931) gives a good discussion of the polar 

 filaments that are found on the eggs of Cystidicola 

 stigmatura. In no case were fewer than four present, and 

 the majority of the eggs possessed from eight to twenty. 

 The variable number, and differing length of these struc- 

 tures, is apparent from Skinker's figures. Not all mem- 

 bers of the genus Cystidicola possess filaments, however, 

 since Hunter and Bangham (1933) report their absence 

 in Cystidicola lepisostei. Figure 141F shows the egg of 

 Cystidicola stigmatura drawn from paratype material. 

 The filaments, as in the case of Tetrameres, are derived 

 from the protein coat. Van den Berghe (1935) observed 

 both terminal and lateral filaments on Cystidicola farionis. 

 They are similarly present over the surface of the egg of 

 Rhabdochona ovifilamenta as well as occurring in polar 

 tufts (Weller, 1938; Fig. 141M). 



Van Beneden (1871) was the first to observe polar 

 filaments in species of Ascarophis. He states that the 

 eggs are distinguished from those of other nematodes by 

 the presence of two filaments which garnish one of the 

 poles. Nicoll (1907) likewise observed these structures. 

 Cobb (1928) notes their absence in the uterine eggs of 

 Ascarophis helix. Baylis (1933) includes them as a 

 generic character in his recharacterization of the genus 

 Ascarophis in spite of their apparent absence in the 

 eggs of some species. 



Polar filaments have likewise been observed in the 

 genera Spinitectus and Metabronema. The condition in 

 Metabronema magmim is worthy of mention since in this 

 species two filaments arise from -button-like opercula at 

 each pole (Fig. 141H). 



Operculation is a fairly common phenomenon among 

 the eggs of the Spiruroidea. The button-like opercula of 

 Metabronema magnum have already been mentioned. The 

 eggs of Hedruris siredonis have opercula suggestive of 

 the Trichuridae (Chandler, 1919). Baylis (1931) finds a 

 similar condition in Hedruris spinigera. Some spiruroid 

 eggs are truncate at both poles and the opercula de- 

 marcated by sub-terminal lines of fracture. Ransom 

 (1904) reported this to be the case for Oxyspirnra 

 mansoni (Fig. 141L). It can be seen even more clearly 

 in the eggs of Ascarops strongylina (Fig. 141K). In 

 Gongylonema pulchrum the opercula are indicated by a 

 thinning of the egg envelope with no lines of fracture 

 being visible (Fig. 1410). Foster (1912) reports bipolar 

 lines of fracture in the eggs of Physocephalus sexalatus 

 (Fig. 141J) but they were not visible in our studies. 

 The egg of this species is truncate at one end and pos- 

 sesses a lenticular operculum. The other end is somewhat 

 attenuated and has a zone of separation between the 

 chitinous shell and the protein coat. The area is not, 

 however, suggestive of an operculum. 



In the majority of the Spfruroidea the egg envelope 

 is smooth and the contours regular, but mammillation 

 and rugosity of the shell occur in the eggs of some 

 species. Chandler (1919) repoi-ts the presence of two 

 prominent, longitudinal ridges or "mammillae" running 

 down the sides of the eggs of Hedruris siredonis (Fig. 



1410). Mammillation in Physaloptera ortleppi ortleppi 

 is expressed in the form of spinulation of the outer 

 membrane. (Fig. 141P). The eggs of Protospirura 

 numidica (Fig. 141C) are weakly mammilla ted, sugges- 

 tive of the condition seen in certain well-known ascarid 

 eggs, for example Toxocara cati or Parascaris equor- 

 um. A lesser degree of mammillation is seen in the 

 rugosity of the shell of eggs of Haplonema }ia/mulatum. 



Brumpt (1931) shows a peculiar .condition in the egg 

 of Protospirura bonnei. These eggs are described as 

 enclosed in a gelatinous sheath which sharply separates 

 the egg from the surrounding debris. Apparently the 

 sheath described is the slightly condensed uterine secre- 

 tion forming a gelatinous protein coat similar to the 

 condition found in many nematodes in the ovarian portion 

 of the uterus. For example in the eggs of the filarioid 

 worm Hastospiculum sp. from Erpetodryas fu-scus, the 

 eggs from the ovarian region of the uterus contain a 

 slightly condensed, irregular protein coat (Fig. 141R-S) 

 while those from the vaginal portion have the protein 

 cuat condensed as in the eggs of other species. It is 

 conceivable that varying degrees of consolidation of the 

 protein coat at oviposition are to be found among the 

 different species of roundworms. 



FiLARloiDEA. (R. O. C). Wide bionomic differences 

 occur in the development of the Filarioidea. Many so- 

 called viviparous species are known, some of which have 

 been discussed in the section on ovoviviparity. The ex- 

 tent to which true viviparity occurs is a question which 

 can be determined only on the basis of further research. 



The eggs of ovoviviparous species are thin-shelled and 

 contain usually but two membranes, the chitinous shell 

 and the very delicate vitelline membrane. They usually 

 have a smooth surface and are spheroid or ellipsoid in 

 outline, as in Dirofilariu immitis (Fig. 141T), Onchocerca 

 fasciata (Vide Badanine, 1938) or Onchocerca volvulus 

 (Vide Blacklock, 1939). Intra-uterine shedding of the 

 egg membranes has been observed by Augustine (1937) 

 in the case of Vagrifilaria columbigallinae, and probably 

 occurs in other species. 



Oviparous species of Filarioidea are about equally as 

 numerous as the ovoviviparous forms. The eggs are 

 similar to those of the Spiruroidea in that they possess 

 a protein coat, contain a coiled embryo at the time of 

 discharge and are usually thick-shelled. As in the 

 Spiruroidea considerable variation of morphology exists. 



Baylis and Daubney (1922) describe the peculiar egg 

 of Hastospiculum macrophallos. The eggs have a charac- 

 teristic barrel shape, are thick-shelled and embryonated. 

 Curious annular thickenings are present at each pole 

 giving a superficial resemblance to the trichuroid type. 



Chitwood (1932) describes the eggs of Hastospiculum 

 setiferum as nearly spherical and embryonated in ntero. 

 Hastospiculum onchocercum has eggs of the same type 

 with a "simple" shell. Chandler (1929) describes the 

 eggs of Hastospiculum spinigerum as having a thick 

 shell, further thickened into a collar near each end, the 

 ends being covered by thin opercula; they contain devel- 

 oped embryos while still in the uteri. Figures 141R and 

 S show the eggs of Hastospiculum sp. from Erpetodryas 

 fuscus. Two different stages of intra-uterine development 

 are seen. In Figure 141R the eggs were taken from the 

 ovarian portion showing the partially condensed protein 

 coat. The coat of the formed egg is seen in Figure 141 S. 



Some genera apparently contain both oviparous and 

 "viviparous" species. Walton (1929) describes two new 

 species of the genus Foleyella. Foleyella ranae is reported 

 as being viviparous, well developed embryos being pres- 

 ent in the uterus. Foleyella americanus is implied to be 

 oviparous since embryonated eggs are described as o,- 

 curring in the lower uterine region. Similarly Walton 

 (1935) noted eggs occurring in the uterus of Isociella 

 neglecta whereas most of the members of the group have 

 been considered to be viviparous. It is our opinion that 

 in the case of both Foleyella amcricanum. and Isociella 

 neglecta that Walton's specimens were not entirely ma- 

 ture and both species are actually ovoviviparous. 



Ransom (1904) describes the eggs of Aprocta cylindrica 

 as elliptical and those of Aprocta orbitalis as thick-shelled, 

 the mature eggs being embryonated. Caballero (1938) 

 notes a double, thin shell for the oval eggs of Aprocta 

 travassosi. The eggs of Filaria martis have been described 

 as having remarkably thick shells with external 

 shagreening. 



185 



