KARLY DEVELOPMENT OF GRAFFILLAGEMELLIPARA 



-A SI PPOSED CASE OF POLYKMBRYt "NY. 1 



J. THOMAS PATTERSON. 



I. INTRODUCTION. 



In th< Bl "k-' Memorial Volume of the Journal of I-'..\-f>eri- 



:<il /"".'";; v, Vol. o,, 1910, Professor Edwin Linum rep--n- the 

 li-.o\.T\ <-t a very interesting viviparous rhabdoccele commensal 



with i In i unmon ribbed mussel, Modiolus plicatnlns, found along 

 tin- All. mti< coast. Dr. Linton refers this worm to the ^eiui> 

 unl on account of its peculiar method of producing 

 eml-iAo- in pairs, designates it by the name Gra' nielli {tarn. 



So I'.ir aa ui know the only other statement in the litiT.utiiv ih.it 

 could l-i- interpreted as referring to this interesting turbellari.ni 



-nnd in .1 -horl j);i[x?r by Nicoll, '06, entitli-d "Notes 

 I I- in. it... I. I' twites of the Cockle (Cardium eti id 



( Mytilu\ filn'. 



Ni "II ' in his Fig. 7) what he calls a trem.ii'>dr -\n<\^ . 



i tin- li\t r i if the cockle, but it is quite clear fmm Linnm'- 

 \\ciik ih.it In i- in error in calling this specimen .1 sporocyst. 

 \\li.n he in .ill probability had was a specimen <-i .1 species <>t 

 tnrl ifll. iri. in ( l<i-ely related to if not identical \\ith (/'. -i-nifllifHini. 

 1 hi- i- e\i< l-iii IP-MI the fact that his figure >h.-u- the pn-M-n. r 

 nl" p.iiifd i-iiil>r\os, as well as a pharynx, \\hich .ilmu- umild 

 elude the case IP-ID the categorx' of sporoi\-i-. 



l.iin-iM'- |M|n-r gives an account of the more m-n.T.il t"r,itin 

 nl" tin- \\onn. I nit leaves several important questions unanswered, 

 .iMioii;^ uhiih may be mentioned the fnllt>\\ iiu : i ll.-u i> iln 

 \t-lk df]io^ititl in the ova? (2) How do the -pi TIM- reach the 

 "sperm-sac"? ; Is the species protandnm >. J 4 \\IKTC. m- the 

 3 lVnili/rtl. J 51 Finally, and mo>t importani of all, How do 

 tin i\\o cmlir\ os in each capsule ari- 



In p-^.ird to thi- last point, Lintt-n -nggests that \\v may have a 



I'K-in tin- M.uiii' ':i'l tin- /<">l"i;i'a tin- 



I ni\ ntril-iH: 109. 



173 



