The family Koellikeriadae. 165 



portioii and escapes fiom view before it reaches its point of outlet. 

 Better sections niight still reveal tliese fading- terminations but in 

 the two pairs stiidied in series tlie contrast was very strikinj?. It 

 may conceivably be the result of the functioning of one worm as 

 a male and the other as a female during- which the remaining sexual 

 function of each was held in abej^ance. It reminds one of the 

 Statement of van Beneden in regard to N. ßarina that the smaller 

 worm of the pair has less numerous eggs than the larger and that 

 these are not yellow as they are in the large one. 



The eg-gs are very small (about 0,01 mm) elliptical: some of 

 them contain stainable material while others seem to be mere empty 

 Shells. They are present in enormous numbers. 



The skin is delicate and thin, supplied as usual with many 

 secreting cells. The body musculature is extremely pooi-ly developed 

 — indeed except in the anterior end of the body it can hardly be made 

 out at all. Even about the head the longitudinal and oblique fibres 

 are extremely delicate. The parenchj^ma in the head end is composed 

 of large swollen cells with small nucleus much as described by 

 Maclaken. In the posterior parts it is scarcely evident. 



The Worms seem to arrive at complete sexual maturity within 

 the cyst and evidently copulate there. No mode of egress was 

 demonstrated. They are not covered with a sheath such as van Beneden 

 described but lie quite free in the cyst. 



The outer wall of the cyst is composed of a pretty dense flbrous 

 tissue within which there is developed a most highly vascular lining. 

 From this lining there run partitions and films of exceedingly 

 richly vascular tissue among the folds of the worms evidently to 

 supply them with oxygenated blood. In section one sees this mem- 

 brane as a closely beaded band each bead representing a distended 

 capillary of the host carrying fresh blood. It might be imagined 

 that in that way an adequate supply of nutriment and oxygen could 

 be brought to the worm even if it made no attempt to actually 

 suck blood from this film — an idea which the character of its 

 alimentary tract and its emptiness seem to go far to prove. 



This form seems to belong without doubt to the genus Nematoho- 

 thrium although it diifers in so many points from N. niolae which 

 Maclaren has described and from the forms described by van Beneden 

 and MoNiEZ although their descriptions are rather too meager to allow 

 of accurate comparison. 



These are trematode worms resembling the genus KoelliJceria 



