98 PROCEEDINGS OF THE NATIONAL, MUSEUM. 



TETRARHYNCHUS ROBUSTUS Linton. 



1800, pp. 855-857, pi. 14, figs. 7-9. 



1900, p. 276. 



1901, pp. 430, 431, 483, 434, fig. 242. 

 1905, p. 341. 



1911, p. 589. 



llecord of this species not heretofore published : 

 Adult stage. 

 Dasyhatis centrura. 



1905, August 20 : 1, with several fragments. 



(U.S.N.M., Helm. Coll. 7727.) 



Larval stage. 



Echeneis naucrates. 



1920, August 21 : 2 globular cysts, 1 mm. in diameter, from serous 

 coat of stomach ; 1 fish examined. 



SCOLEX POLYMORPHUS Rudolphi. 



Larval Tetrabothria, 1S89&, pp. 453, 454, pi. 6, figs. 6-9. 

 Larval Echeueibothria, 1897&., pp. 789-792, pi. 61, figs. 4r-15. 

 Larval cestodes, 1900, pp. 276, 277, 279-284. 



Scolex polymorphux Rudolphi, 1901, p. 413 (page references to 28 hosts). 



1905, pp. 326, 332-333 (page references to 

 34 hosts). 

 1907d, p. 101. 

 190S&, pp. 162, 175. 

 1911, p. 588 (39 hosts named). 



This name is i-etained for convenience, although it is to be in- 

 terpreted, not as an ordinary specific designation, but rather as the 

 name of a group of larval cestodes, in which many species, and even 

 genera, are represented. 



The complete life history of these forms has not been made out. 

 They appear to be scoleces which have passed the encysted stage in 

 some other, probably Arthropod, host, and are free in the alimentary 

 canals of their hosts, as sojourners, for a short time in teliosts, as 

 potential adults in such selachian as may be adapted to be a final 

 host. 



See the admirable paper by Dr. W. C. Curtis.^^ 



Following are records of finds of these cestodes, details of which 

 have not hitherto been published. Collections in the months, Sep- 

 tember to June, inclusive, for the most part, made by Vinal N". 

 Edwards. 



»8 Journal of Morphology, vol. 22, pp. 819-853, pis. 1 and 2 (September, 1911). 



