487] PSEUDOPHYLLIDEA FROM FISHES— COOPER 199 



garis he found young strobilas, still possessing the rounded caudal piece but no 

 neck, with the habit of invaginating their scolices. In a Salmo salar he found on 

 July 4th similar young " scolices " (plerocercoids) not only free in large numbers 

 in the intestine of the host posterior to the pyloric ceca but also present along 

 with the anterior ends of adult strobilas in the ceca themselves. Again in 

 June he found a great many young strobilas in S. alpinus. These facts, togeth- 

 er with the further fact that the adult worms have been found in the hosts 

 during every month of the year, points to infection of the final host with the 

 pleroceroids at all times of the year. Of chief interest in this connection is 

 the finding by Schneider (1902:28) of young plerocercoids 2 to 7mm. long 

 free in the stomach and intestine of Clupea harengus membras L., which he 

 believed to be the young stages of Bothriotaenia proboscidea (Batsch), as he 

 called the species. They were found in greater numbers towards the latter 

 part of June than at other times during the summer. Concerning the sig- 

 nificance of the location of the larvae in these herring, he said: "Daher muss 

 ich armehmen, dass dieser Fisch nicht der erste, sondern der zweite Zwischen- 

 wirth des Bandwurmes ist. Erster Zwischenwirth, in welchem der Wurm sein 

 Cystenstadium durchlauft, muss wohl ein Arthropode (Kruster oder Insecten- 

 larve) sein, der dem Ostseeheringe sehr oft zur Nahrung dient. Falls meine 

 Annahme richtig ist, woran ich nicht zweifele, das Clupea harengus membras 

 L. derjenige Zwischenwirth ist, mit dem der Ostseelachs direct die Larven 

 von B. proboscidea in seinen Darmkanal aufnimmt, so erklart sich leicht das 

 Zustandekommen solcher Wasserinfectionen, wie sie an den Ostseelachsen 

 beobachtet werden." Liihe (1910:12) briefly reviewed the findings of these 

 bothriocephalid larvae in various hosts up to date and pointed out that those 

 of Diphyllobothrium latum have often been confused with those of A . crassum 

 and that in many cases it is doubtful whether either was certainly at hand. 

 Ward (1910:1184) reported the species from Salmo salar sebago and Cristovomer 

 namaycush, but was unable to throw any hght on the life-history altho he in- 

 vestigated the Sebago smelt as the possible intermediate host. No larvae were 

 found in the latter, but concerning the infection of the final host, he said: 

 "This is worthy of note that all of these parasites were full grown; not a 

 single specimen was found which was not discharging ripe proglottides. 

 Consequently the infestation must have taken place somewhat earlier in the 

 year. " The youngest lots of material studied by the writer were two taken 

 from Lota maculosa from Lake Ontario, off Port Credit, near Toronto, on 

 Nov. 5 and 8, 1912, and one from the intestine of a young Cristovomer namaycush 

 from the same locality on the latter date. The lot from the lake trout con- 

 tained all stages from that shown in figure 50 to the largest which by compari- 

 son with adult specimens from the same host were found to belong to this species. 

 While no stages were found between that shown in figure 52 and that shown in 

 figure 50 altho two others were only very slightly larger than the latter, it seems 

 reasonable to consider the latter itself to belong to this series and to represent 

 the earliest stage of the same. Figures 53 and 54, two later stages, are 

 given to show the manner of beginning of the segmentation and the early 



