26 



" TERRA NOVA" EXPEDITION. 



in the oesophageal and intestinal diverticula, but these are smaller. The vaginal 

 opening is 4 mm. from the head-end, the worm measuring 25 mm. in length. The 

 vagina is strong and muscular, and the uterus runs caudal wards from this as a single 

 narrow tube. The eggs are iu very well-marked groups; they measure O'l mm. by 

 0'06 mm. The tail ends in a finger-shaped process, and the anus is 0'4 mm. from 

 its tip. # 



3. Kut hi cciii i radii ltd (v. Linst.). (Text-fig. 2.) 



Ascaris radiata, v. Linstow, 1906 (?1907). 

 ,, falcigera, Railliet and Henry, 1907. 



Host. — The Weddell's Seals throughout the Antarctic Zone appear to be heavily 

 infected with this parasite. It has been reported in large numbers by the Scottish 

 National Antarctic Expedition and by the first French Antarctic Expedition. It is 

 suggested by Railliet and Henry that some of the forms collected by the Germans in 

 South Georgia in 1882-3 belonged to this species, although ascribed to Ascaris osculata. 



Parasite. — The parasites are typical Ascarids when seen with the naked eye ; 

 i.e., they are stout wiry round worms of a whitish colour in the preserved state and 

 showing a ventral hook-like twist of the posterior end in the males. There is a wide 

 range of size in the material at our disposal, this being due to the relative maturity of 

 the individual specimens. A mature male measures about 12 •Omm. long, a female 

 13—20 mm. lung. The body has a diameter of from 1 ■ 5 mm. to 2"0 mm. The mouth 

 is guarded by three large lips, quadrate in outline and with a lateral cuticular ledge 

 prolonged from the free angle. There are three sickle-shaped interlabia which, in 

 specimens in spirit, showed a fine striation of the internal substance of the cuticle. 

 Upon tli is feature v. Linstow based the specific name. 



The results < if < >ur examination confirm in the main the details of structure and the 

 minutiae of measurements given by Railliet and Henry and by v. Linstow. In a small 

 male specimen of 12 "0 mm. the oesophagus is 1*6 mm. long and its greatest diameter 

 is 0 " 1 9 mm. There is posteriorly an oesophageal appendage containing the dorsal 

 oesophageal gland. This extends 0 ' 7 mm. behind the junction of the oesophagus with 

 the chyle-intestine. This organ is stated by v. Linstow to be of the length of the 

 oesophagus. Railliet and Henry mention the presence of the structure, but give no 

 measurements. From the chyle-intestine there passes forward a blind caecum, 0 ' 9 mm. 

 in length, reaching just beyond the middle, of the oesophagus. 



The chyle-intestine is very voluminous, and its walls are much folded. At 1 ' 6 mm. 

 1 >ehind the oesophageal valves are the closely packed coils of the testicular tube. These 

 coils occupy the succeeding 3 •0 mm., and thence the tube runs directly backwards to 

 the anogenital opening (text-fig. 2, a), 0*19 mm. from the tip of the tail. The spicules 

 are very similar in size and shape. They are transparent and colourless rods, 2 • 6 mm. 

 in length, and present somewhat characteristic outlines. There is a solid strengthening 

 portion running along the whole length of the spicule to become the blunt tip. In the 



