156 ILLINOIS BIOLOGICAL MONOGRAPHS [444 



In external appearance this species is characterized by the globose nature 

 of the scolex and the serrate margins of the strobila, the former of which was 

 the basis of Leuckart's (1819:45) specific name and which with the latter was 

 emphasized and included in the diagnoses given by all the authors after Rudol- 

 ph! (1819). But another important character which also assists in the ready 

 recognition of the species is the presence of spurious articulations, which, how- 

 ever, are evidently not those mentioned collectively by Wagener (1854:69) as 

 "articulatio spuria." 



The scolex (Figs. 29-31) is divided by two longitudinal marginal grooves 

 into two dorsoventral hemispheres, the bothria. The latter were considered 

 by Rudolphi (1819:130, 477) and others to be marginal in position, but many 

 years elapsed before this error was finally and definitely corrected by Liihe 

 (1899:35). F. S. Leuckart (1819:45) rightly described and figured the scolex as 

 "medio marginali sulcato, foveis lateraUbus. ..." and "Die Randflache 

 des Kopfes ist breiter als die Seitenflache, die mittelfurche jener ziemhch tief, 

 und bi det an jener Seite eine erhabene, in der Mitte hellere Wolbung. " It seems 

 that Molin (1881:235) fell into the error of considering the marginal or lateral 

 grooves, separating the bothria, to be the bothria themselves, as indicated in 

 his diagnosis: "Caput magnum subglobosum, utrinque sulco longitudinaH 

 laterali, apertura centraU bilabiata antica, bothriis ovaHbus, subter min- 

 alibus, marginahbus, longis"; and in his " Osservazione 2" he said: "Quan- 

 tunque la testa sia molta grossa ed opaca, cio non per tanto potei distinguere 

 il solco menzionato da Diesing [1850:587] il quale pero corrisponde ai lati 

 e non ai margini del corpo, e sembra dividere la testa in due emisferi, Ognuno 

 di questi porta ima fossetta oblimga, ovale, che si estende dall' apice a due terzi 

 della lunghezza del corpo, e sembra di quattro quadrant! suddivisi da due solchi 

 che s'incrocciano. " It is evident from his figure 2, Taf. V, that the "fossetta 

 oblunga" is the entrance to the bothrium, but he does not seem to have 

 observed the actual opening. Matz (1892:103) expressed the opinion that the 

 bothria of this species are dorsoventral in position, while Ariola (1896:280) evi- 

 dently on the basis of former descriptions placed the species among those of 

 the genus Bothriocephalus Rud. with "Botridi marginali." Stossich (1898: 

 115) also described the scolex as " ... subglobosa, con botridii marginali, 

 subterminaU, ovato-allungati. " Ariola (1900:398) finally corrected his own 

 view of the external structure of the scolex by saying that "Un esame anche 

 superficial dimostra pero che la posizione degU organi di fissazione non e equale 

 fu ritenuta, perche ciascun d'essi corrisponde ad una faccia larga dello strobila, o 

 como si dice, sono dorsoventrah. I pretesi botridii marginali sono dati da un 

 solco circulare, abbastanza profondo, che corre a guisa di un meridiano attomo 

 alio scolice globoso, passando per I'apice, e dividuendolo come in due emisferi, 

 imo destro a I'altro sinistro," thus evidently ignoring the fact that Liihe had 

 already (1899:25) performed the service for students of the group, as he later 

 pointed out with justifiable emphasis (Liihe, 1901:414). 



The bothria in this species are sac-like structures, formed (phylogenetically) 

 as indicated in the generic diagnosis, by the rolling together of their edges or 



