Some Points on the General Anatom y of Gyrocotyle. 719 



ally valuable for its description of the living animal. I shall have 

 occasion to refer to his work under the various special sections of 

 this paper. 



Braun (1894) in his discussiou of the Cestodaria summarized 

 the facts already determined regarding the structure of Gyrocotyle 

 and emphasized the trivial and uncertain character of the features 

 nsed in distinguishing the two species previously reported. 



Haswell (1902) published a brief tho accurate study of a 

 second species from southern seas. He endeavored to establish the 

 specific character of various forms on the basis of the relative posi- 

 tions of the sexual pores, the spines, the eggs and embryos, and also 

 on certain finer details in the structure of the reproductive System 

 which will be discussed in a later section of this paper. 



Kofoid & Watson (1910) from studies on the living worm found 

 that Gyrocotyle lies with its ventral face against the mucosa, attached 

 by the rosette, or as they term it the scolex, which they regard as 

 posterior while the mobile anterior end is free and bears the aceta- 

 bulum. The face defined as ventral is normally always turned to 

 the substratum, possesses heavier musculature and more abundant 

 nerve supply. It bears the vaginal pore but not the uterine pore 

 which is dorsal. The ventral surface as here defined has heretofore 

 been regarded as dorsal. Observations on the living worm showed 

 them that the acetabular end conducts itself as the functional 

 anterior end. The rosette end is passive. This orientation is 

 supported by the morphology of the nervous System which further 

 shows evident similarity to that of planarians and of some hetero- 

 cotylean trematodes. 



Watson (1911) elaborates the views already noted as advanced 

 in the Joint paper and discusses in detail the structure of the 

 species found in the California Chimaeroid. 1 ) She distinguishes four 

 species including one new form, the type most frequently found in 

 California. The most important part of the paper is undoubtedly 

 the extended study of the hitherto relatively unknown nervous 

 sytem in Gyrocotyle. On the basis of her findings she regards the 

 cestode scolex as "a posteriorly situated organ of attachment''. 



1) I am informed by Doctor B. W. Evermann that this is the 

 same species which I examined in Alaska, and that it should be designated 

 not Chimaera collei but Hydrolagus collei. 



