408 Zoological N. Y. Zoological Society. [I;20 



short distance from its posterior end in which the ova seem riper 

 than elsewhere. Just behind this portion of the ovary may be 

 seen a rather large seminal reservoir from which a tube passes 

 around the ovary to join the oviduct just anterior to the ovary. 

 Anterior to the ovary and duct from the seminal reservoir, a 

 small vitelline duct is seen to join the oviduct, after which there 

 is formed the ootype, which merges into the shorter division of 

 the uterus. The eggs in this first portion of the uterus are imma- 

 ture and it is not until they have proceeded to the anterior end 

 of the worm, thence to the tail and return to the head that they 

 seem fully developed and ready to be laid, or discharged through 

 the genital pore. They are small — .005 mm., oval yellow, with- 

 out filaments and very numerous. 



The vitellarium, also in tubular form, extends almost the 

 whole length of the worm; it is somewhat nodular and stains 

 with carmine a yellowish brown. No vagina has been seen nor 

 has a shell gland been found. 



The male genitalia consist of a tubular testis which extends 

 about two-thirds the length of the worm beginning near the 

 anterior bend of the uterus. It stains pinkish. At the posterior 

 end of the testis the vas deferens is given off ; this is as usual a 

 convoluted tube which extends anteriorly to the atrium situated, 

 as viewed from the ventral surface of the worm, behind the 

 mouth. No cirrus is visible. 



The characters of the worm for the purposes of classifica- 

 tion may be given as follows: Flat, ribbonlike, very narrow 

 throughout, but very attenuated towards the anterior end; 

 uterus in two or three tubes extending uncoiled throughout 

 nearly from one end to the other; the ovary also tubular, but 

 not nearly so long as the uterus. Vitellarium and vas deferens 

 are also single tubes; the former nearly half as long as the 

 uterus. The testis is also tubular and the vas deferens extends 

 through nearly three-fourths of the length of the worm to the 

 end at the genital atrium at the mouth. Living in great num- 

 bers, tangled together under the mucosa of the gill cavity of 

 marine fishes, Sarda, etc. 



This worm was found in material at the U. S. Bureau of 

 Fisheries laboratory, at Wood's Hole, and the work in its study 

 was carried out at that laboratory. 



