478 ^' '^ NICKERSON, 



lust a more or less cuiuplicateii series ul ehaiiges which have been 

 retained by its relatives inhabiting salt water. 



Cunningham suggests that the eggs of Sfichocof/jle are probably 

 taken in by the bibster with its food, and that the young worms are 

 hatched from them in the intestine. The fact that the cysts of 

 Stichocoti/le have been found only near the posterior end of the intes- 

 tine suggests to me quite as strongly that a free-swimmiDg larva has 

 entered the intestinal tract through the anus and thus become en- 

 cysted in the wall of the intestine. There is certainly nothing njore 

 improbable in this proposition than in the well-known seeking out of 

 the respiratory chamber of a snail by the miracidium of our common 

 fresh water Distomes. What the course of development actually is in 

 this interesting form we can expect to know only when the adult 

 shall have been found and the development traced from the egg. This 

 I hope ultimately to accomplish. 



In conclusion I would here express the sincere gratitude which 

 I feel to my instructor Dr. Edward L. Mark for his many courtesies 

 both in the course of this work and throughout my connection with 

 the department of which he is the head. 



Cambridge, May 10, 1894. 



Literature. 



Brandes, G., '92, Zum feineren Bau der Trematodeii , iu : Zeitschr. 1'. 



wiss. Zoologie, V. 53, p. 558—577, tab. 22. 

 LEjTftNYi, C. V., '81, Ueber den Bau des Gastrodiscus polymastos 



Leuck^vkt, in: Abhandl. Senckenborg. Naturf". Gesellsch., V. 12, 



p. 125—146, 3 pl. 

 Looss, A., '93, Zur Frage nach der Natur des Körperparenehyms bei 



den Trematoden, nebst Bemerkungen über einige andere, zur Zeit 



noch offene Fragen, in : Ber. Vorhand!. K. Sachs. Gesellsch. Wiss. 



Leipzig, Matli.-Phvs. Cl., V. 45, j). 10-34. 

 MontickllLI, f. S., '92, Cotylogaster Michaelis n. g. n. .sp. o revisiouo 



degli Aspidobothridae, in: Festschr. R. Leucka.bï, p. 108—214, 



tab. 21, 22. 

 — '93, Studii sui Trematodi endoparassiti. Primo contribute di osser- 



vazioni .sui Distomidi. Jona. Znolop^. Jahrb., Snppl.-Hft. 3. 220 pp., 



8 Taf. 



