18 Mindeskrift for J. Steenstrup. XXV. 



The oesophagus is divided into two distinct parts. The cephahc part is rather short 

 and slender and suddently passes into the other half which is conspicuously thicker 

 and longer with fairly uniform width throughout the length, and only increasing in- 

 conspicuously in the hindmost part. The proportion of the length in the two halves 

 is about 1 to 6. In an oesophagus, the whole length of which measured 2,7 mm. the 

 diameter was found to be 26,4 (x in the slender part whereas in the thicker half a little 

 anterior to its passing into the chylus-intestine the diameter was found to be 52,8 fi or 

 exactly twice the size of the front part. 



The length of the oesophagus differs conspicuously as far as the two sexes are 

 concerned. In a female specimen the length of which was 6 ctm. the oesophagus 

 measured 7 mm, coming thus to 7'^ of t^e whole length of the worm. In a male 

 of V-h ctm. the oesophagus measured 2,8 mm. or about ^4 of the length. 



Round the middle of the front part of the oesophagus the nerve-ring is very di- 

 stinct both in the fully developed worm and in the larva (see PI. III fig. 17, and 

 PI. IV fig. 28). In the male specimen of l^/s ctm. mentioned above, the diameter of 

 the nerve-ring measured 45 ^u. In optical sections the central part of the nerve-ring is 

 seen to consist of a granulated substance surrounded by an apparently homogenous 

 coat, which presents itself exceedingly thin on the side facing the oesophagus. Similar 

 spurs of sarcoplasma as described by Looss in the Filaria loa are found reaching from 

 the muscular layer towards the nerve-ring (fig. 18). 



The oesophagus is as usual marked off from the chylus-intestine by a constriction, 

 the chitin-intima, however, being traceable somewhat further down. 



As far down as this chitin-intima reaches the intestine presents a peculiar differ- 

 entiation with faint transversal striæ, probably consisting of muscular tissue. Gaudal 

 to this part some conspicuous intestinal valves are observed, sometimes arranged in two 

 rows as may be seen in the fig. 23. 



On the whole, the chylus-intestine is but slightly developed, its width being almost 

 corresponding to that of the thin front part of the oesophagus. Most frequently it 

 appears as a fme line throughout the worm; only its hind part is sometimes rather 

 sinuous and the lumen here somewhat more dilated than is the case in the rest of 

 the intestinal canal. Rectum decreases in width (fig. 19). The anal musculature is well 

 developed. The intestine in the female opens at a distance of 210 fi from the 

 tip of the tail, the shape of which is regularly conical with rounded point. The 

 tail, as well as the front part of the worm, shows a great power of contraction. 

 On the specimen, pictured on the fig. 19, the tail has fairly its natural shape 

 and length; when contracted it will only present half the length and become thick 

 and folded, often ventrally bent. In the male, which has a large bursa and only 

 one aperture for the intestinal and genital duet, the anus is situated at a distance 



