456 STANLEY C. BALL 



on either side below the median frontal plane, extending from 

 anterior fifth to middle of the body; two extensively branched 

 and anastomosed vitellaria; ovaries and vitellaria not joined 

 but closely apposed at their proximal ends where they meet 

 the rudimentary oviducts; testes paired, situated one on each 

 side just laterally and posteriorly to the pharynx; vasa defer- 

 entia short, arising from the inner posterior margins of the testes 

 and opening into the seminal vesicle on its anterior surface; 

 bursa seminalis lacking; viviparous, the young developing, 

 usually in pairs, inside capsules of which as many as forty may 

 be present at once in the mesenchyme of the mother; young 

 break out of capsules and swim about in parent until they 

 emerge through body wall or intestine; rolled up capsule shells 

 remain in the 'mesenchyme. 



Paul Hallez has given ('09). a detailed account of his ob- 

 servations on Paravortex cardii, a Rhabdocoele belonging to a 

 genus closely related to Graffilla. The resemblance between 

 Linton's and Hallez's species, as will be indicated below, is 

 very striking. 



The genus Paravortex was established by Wahl ('06) for a 

 species of Turbellarian which is parasitic in the alimentary 

 canal of Scrobicularia tenuis and S. piperata. According to 

 Wahl it was discovered and inaccurately figured by Villot. 

 Von Graff later called this parasite Macrostomum scrobiculariae, 

 but Wahl asserted that it was worthy to be placed in a new genus. 

 This he called Paravortex. He also found von Graff's Pro- 

 vortex tellinae to be identical with it. 



Wahl ('06) briefly described the new genus Paravortex in 

 the following words: 



"Dalyelliide mit am Vorderende des Korpers gelegenem 

 Pharynx, paarigen Keimstocken, verzweiten Dotterstocken, 

 rundlichen Hoden und ventral vor der Korpermitte gelegener 

 Geschlechtsoff nung. " 



In the same paper Wahl characterizes the genus Graffilla thus : 



''Dalyelliide mit am Vorderende des Korpers gelegenem 

 Pharynx, paarigen Keimstocken von der Form gewunderen 

 Bander und davon getrenntren Dotterstocken. Geschlechtsoff- 

 nung mittelstandig, Hoden schlauchartig." 



