184 ILLINOIS BIOLOGICAL MONOGRAPHS [472 



mende Form als eine getrennte Species auf zufassen unter deni Namem ' rugo- 

 sa' (Bothriocephalus rugosus 'Rud. = Dibothriuni rugostmi Diesing, u.s.w.), ob- 

 gleich die unterscheidenden Merkmale zwischen B. proboscidea und B. rugosa, 

 die Riggenbach in seinen 'Bemerkungen ueber das Genus Bothriotaenia Railliet' 

 iibersichtlich zusammenstellt, recht unbedeutend sind und vielleicht doch 

 noch in Rahmen der Variationsbreite einer einzigen Species untergebracht wer- 

 den konnen;" and, as regards the latter, in a footnote: "Die von M. Liihe 

 ... als Unterscheidungsmerkmal vorgeschlagene Lage der Dotterstocke 

 zum Theil {B. rugosa), bzw, auschliesslich {B. proboscidea) zwischen den Langs- 

 muskehi, scheint mir auch nicht genugend constant sein, um als Speciesmerk- 

 mal verwandt werden zu konnen. " For material from Lota vulgaris Schneider 

 described a scolex and segments both similar, as he pointed out, to those of 

 B. proboscidea { = A. crassum). The arrangement of the genital cloacae, 

 irregularly alternating but unilateral for long stretches, the openings of the 

 uteri in a longitudinal furrow, the early form of the uterus-sac and the size of 

 the eggs (64.5 by 50 to 52/x), as described by the same worker, all agree with 

 A. crassum as studied by the writer. In conclusion Schneider said: "Uebri- 

 gens habe ich, wie gesagt, auch an die Examplaren aus dem Museum keine 

 Pseudoscolexbildung bemerkt und zweifle daran, dass B. rugosa und B. gadi 

 ein und dieselbe Art sind," and further, "Es ist mir iibrigens bisher noch nicht 

 gelungen, B. rugosa oder B. gadi in Gadiis morrhua des Finnischen Meerbusens 

 aufzufinden, obgleich ich zahlreiche Exemplare des Dorsches seciert habe, und 

 obgleich B. rugosa in Lota vulgaris hier oft genug vorkommt. Auch das scheint 

 gegen die Identitat der Species B. rugosa mit B. gadi zu sprechen. " 



Thus it is seen that there is considerable detailed evidence that the species 

 from Lota is not the same as that from the marine hosts. One must then go 

 back of Linstow's time in order to determine, if possible, what is the correct 

 name for the latter. Next in retrogressive order is van Beneden's (1871:56) 

 description of A. gadi, confined to a short footnote which deals with Httle 

 more than the pseudoscolex. So far as it goes this agrees with Lonnberg's 



A. rugosum and with the material studied by the writer. Olsson (1867 :54) was 

 obviously deaHng with the same form which he reported from marine hosts only. 

 Diesing (1863 and 1850) copied from Rudolphi, while Cobbold (1858) had the 

 marine form before him, and Baird (1853) had the fresh-water form. In spite of 

 Linstow's objection the writer feels certain that Dujardin (1845) also had the 

 species dealt with here, especially since his measurements of the eggs come 

 nearest to those observed than do those of any other writer. It remains then 

 to enquire into Rudolphi's finding and description, as Leuckart (1819:57) copied 

 from him altho at the same time remarking that "Ist am nachsten mit den 



B. proboscideus verwandt, und, wenn er nicht eine Art mit diesem ausmacht 

 zwischen B. proboscideus und B. sagittatus zustellen." For B. rugosus Rudol- 

 phi (1810:42) described a scolex, comparable to that of his B. proboscideus and 

 to Linstow's description and figure of the organ, no neck, and segments "primi 

 angusti, fere quadrati, insequentes latitudinis ratione habita brevissimi, 

 saepeque inequales, vel hinc inde angustiores; margines obtusi crassiusculi. " 



