244 Dr. W. B. Bcnliain on an 



ifi, at tiiiv rate, a very {it-culiar position for the " liearts " to 

 occupy, 



Perrier {loc. cit. p. 70) states that in the three somites 

 immediately anterior to these intestinal hearts there exist as 

 many pairs of " vdritables coeurs." I believe that he is dealing 

 really with intestinal diverticula, for he states that each ot 

 these organs is distinguishable into two very distinct parts : — 

 (1) a superior, white, opaque, more voluminous region of 

 ovoid form, and communicating at its narrow end with a 

 vessel leading from the dorsal trunk ; and (2) a more ven- 

 trally placed spherical region, with tran?:parent walls, which is 

 swollen with blood, and in relation to the ventral vessel. To 

 quote his words : — " Sur chacun d'eux on distingue deux 

 parties bien distinctes : I'une infdrieure, h. parois transparentes, 

 gonflce par un sang bleuatre coagule, de forme spherique : 

 I'autresup^rieure, blanche, opaque, plus volumineuse, de forme 

 ovoi'de, et s'abouchant par son ])etit bout avec le vaisseau qui 

 conduit an tronc dorsal." 



And he speaks of the inferior retjion as an " auricle " and 

 the superior as "ventricle; " on the walls of the latter, he 

 goes on to state, there can be seen some bluish veins starting 

 from the apex, which soon disappear. 



He was led to the above conclusion owing to his having 

 observed, as he thought, a similar "heart" with ventricle 

 and auricle in Titanus (i. e. Geoscole.r^ Leuckart). 



Now I have examined a specimen of this worm, as I have 

 previously mentioned*, and I find that the organ lying in 

 sfimite xiii., whose relations were accurately described by 

 Perrier, and which he mistook for a " ventricle," is in reality 

 an intestinal diverticulum, having the same essential structure 

 as the a?sophageal glands o^ Lumbricus'f. 



I believe, then, that the three pairs of organs are the 

 characteristic intestinal diverticula whieli occur in this region 

 in the other three species of lihinodrilus. 



The genital organs (fig. 2). — There are two paii-s of rather 

 extensive sperm-sacs (sp.fi.), which meet dorsally to a greater 

 or less extent, and conceal the gizzard, the intestinal divor- 

 ticuhi, and other organs in this region of the body. The 

 anterior sac on each side appears to extend thnnigh somites 

 viii. to xiii., and the posterior through somites xiv. to xvii. ; 

 but more careful observation shows the former to arise in 

 somite xi. and pass forwards into somite vi., and the posterior 

 to extend through somites xii. to xvii. There are two pairs 



* "Studies on Enrtlnvoiuis, I.," Quiut. .Ti uiii. Micr. Sci. xxvi. p. I'.'jO. 

 t Mr. Ikcldind ciuiHrnis my view of the niatler in liif pjier in thiji 

 .fi'Uiniil t'vv Febinaiy nftlie ])ie.<enl year. 



