158 Gr. A. and W. G. MacCallum, 



From all this it is seen that peciüiar conditions prevail in this 

 species, The worm is a cylindrical elongated form which is coiled 

 abuiidantly in a mesliwork of connective tissue. In one specimen 

 there is a pair, in tlie otlier as far as we can see only one individual. 

 The Single individual is a well developed female with obsolescent 

 male organs. In the pair there is one with very distinct and 

 liighly developed male characters and obsolete if any female 

 characters, and another with rather poorly developed female 

 characters and obsolescent testicular masses without any trace of 

 vas deferens. 



The name Koellikeria is retained for this transitional form, 

 although apparently the worm is even more closely allied to the 

 genus Nematobothrimn than to the genus Koellil-eria if one may 

 judge from its body form and from the arrangement of its organs 

 which is precisely that of the Nematobothrium. It furnishes an 

 especially brilliant example of the degeneration and disappearance 

 of organs under peculiar conditions of life and possibly represents 

 a transition toward the monoecious State. 



How cross fertilization has occurred in these specimens it is 

 difficult to surmise for the efficient male is enclosed in a cyst at a 

 distance from the efficient female and has only a rudimentary female 

 in the same cyst to fertilize while the female is isolated except for 

 its own rudimentary male apparatus. 



The wall of the cyst is more fibrous and less vascular than 

 thsit of the Nematobothrium sarclae\ nevertheless there are bands and 

 filaments of highly vascular character which run between the coils 

 and doubtless supply them with nourishment. No distinct opening 

 for egress of eggs etc. could be made out, but this point must be 

 restudied when fresh material is found and sectioned without tearing 

 of the attachment. Still the head bearing the opening of the vas 

 deferens lies just under the perfectly intact outer wall of the 

 capsule as though at least its projection through any external opening 

 was unnecessary and further the fact that the opposite side of the 

 mass wliere both the heads containing the uterine openings lie is 

 the side of firm attachment to the bone so that it seems extremely 

 unlikely that any opening occurred there. The escape of eggs to 

 the outer world must therefore in all probability be thi'ough rupture 

 of the cyst or its digestion after the death of the fish by some 

 intermediate host. 



